Company standarts - Jewelry natural stones

The standard of the Organization of the Service Station "MGC"
"Jewelry natural stones"

1. Introduction. The scope of application.

1.1. The standard of the organization "Moscow Gemmological Center" (hereinafter HUNDRED MGC) is not an industry or national standard. The STO MGC defines the methods of testing jewelry and ornamental faceted stones, including those installed in jewelry, and the information content of gemological reports (conclusions and certificates) issued on the basis of an appeal from an individual or legal entity.

1.2. This standard of the organization applies to loose jewelry and jewelry-ornamental faceted stones, as well as jewelry and jewelry-ornamental faceted stones installed in jewelry, and establishes a set of information reflected in gemological reports (conclusions and certificates) regarding the quality characteristics of jewelry and jewelry-ornamental faceted stones, their classification and terminology.

1.3. The main classification criteria of this standard comply with the requirements of CIBJO «The Gemstone Book»-2015, CIBJO «The Pearl Book»-2015, CIBJO «The Coral Book»-2015, Standards of organizations: «Association «Guild of Jewelers of Russia» HUNDRED 52818945-1-2016 "Jewelry inserts. Information Disclosure Rules», «Gokhran of Russia» STO 45866412-16-2014 «Precious Stones. Terms and definitions.», and are also comparable to «Gokhran of Russia»; STO 45866412-15-2013 "Sapphires, rubies refined by diffusion and/or filled with glass (faceted inserts). Technical Specifications », STO 45866412-11-2009 «Natural processed alexandrites. Technical Specifications », STO 45866412-06-2008 «Natural processed rubies. Technical Specifications », STO 45866412-05-2008 «Natural processed sapphires. Technical Specifications », as well as Technical Specifications of TU-95.335-88 «Natural processed emeralds. Technical specifications".

2. Normative references.

This standard uses the recommendations of the following standards, classifiers and reference books (including dictionaries) with normative references:

• GOST R 1.0-2012 "Standardization in the Russian Federation. The main provisions»
• GOST R 1.4-2004 "Standardization in the Russian Federation. Standards of organizations. General provisions
• GOST R 51293-99 "Product identification. General provisions
• filled with glass (faceted inserts). Technical specifications
• STO 52818945-1-2016 "Jewelry inserts. Information Disclosure Rules"
• ONE HUNDRED 45866412-16-2014 «Precious Stones. Terms and definitions
• STO 45866412-15-2013 "Sapphires, rubies refined by diffusion and/or filled with glass (faceted inserts). Technical specifications
• STO 45866412-11-2009 «Natural processed alexandrites. Technical specifications
• STO 45866412-10-2008 "Natural unprocessed rubies (in raw materials). Technical specifications
• STO 45866412-09-2008 «Natural raw sapphires (in raw materials). Technical specifications
• One hundred 45866412-06-2008 "Natural processed rubies. Technical specifications
• ONE HUNDRED 45866412-05-2008 «Natural processed sapphires. Technical specifications
• TU-95.335-88 "Natural processed emeralds. Technical specifications".
• CIBJO «The Gemstone Book»-2015;
• CIBJO «The Pearl Book»-2015;
• CIBJO «The Coral Book»-2015
• Geological Dictionary. In 3 volumes. Gl.ed. Petrov O.V. VSEGEI Publishing House. C-Pb. 2011

3. Terms and definitions.

3.1. Basic definitions.

3.1.1. Jewelry stones Various natural stones (minerals, mineraloids, rocks and natural organogenic formations) used in the manufacture of jewelry or works of art due to the combination of properties that ensure their beauty, rarity and relative durability, as inserts or independent stone products.

Notes

* The durability of jewelry stones may vary depending on their hardness, strength and stability.

* The term "gemstone" should be used only for stones of natural origin.

* Only the term "jeweler's stone" can be used with terms such as "real", "precious", "authentic" and "natural/natural".

(according to STO 45866412-16-2014 «Precious Stones. Terms and definitions)

3.1.2. Natural stones minerals, (mineraloids), rocks and natural organogenic formations that were formed completely in natural conditions without human intervention and subsequently changed only as a result of their processing (cutting and/or refinement).

(according to STO 45866412-16-2014 «Precious Stones. Terms and definitions)

3.1.3. Minertia A natural chemical compound, usually of a crystalline structure, formed as a result of processes occurring on earth or on other cosmic bodies. … Distinguish between crystalline, metamict and amorphous minerals. … (Geological Dictionary. Gl.ed. Petrov O.V. VSEGEI Publishing House. C-Pb. 2011)

3.1.4. Mineral appearance An elementary taxon of mineralogical classification. A set of mineral individuals possessing the same or similar crystal structure and chemical composition. … (Geological Dictionary. Gl.ed. Petrov O.V. VSEGEI Publishing House. C-Pb. 2011)

3.1.4. Mineral variety A collection of individuals of the same mineral species that differ from other individuals of the same species in some way (chemical composition, some structural details, crystal morphology, coloration, etc.) or have similar crystal structure and chemical composition. … (Geological Dictionary. Gl.ed. Petrov O.V. VSEGEI Publishing House. C-Pb. 2011)

3.1.5. Mineraloid A solid (metamict, glassy, polymeric, gel) mineral substance, including a variety of mineral, homogeneous in chemical composition and physical properties, formed in the same way as minerals [completely in natural conditions without human intervention]. … (Geological Dictionary. Gl.ed. Petrov O.V. VSEGEI Publishing House. C-Pb. 2011)

3.1.6. Rock is a dense or loose aggregate of mineral substances (minerals and mineralloids), which is a product of geological processes. Rocks may also contain liquid minerals and gases. … (Geological Dictionary. Gl.ed. Petrov O.V. VSEGEI Publishing House. C-Pb. 2011)

3.1.7. Natural organogenic formation A solid product of vital activity or a part of the body of living organisms (plants, fungi and/or animals) that has not undergone fossilization processes, as well as suitable for use (including after pretreatment) as inserts in jewelry or household products. (according to CIBJO «The Pearl Book»-2015; CIBJO «The Coral Book»-2015)

3.1.8. Insert (faceted) faceted [or otherwise processed] stone [natural, synthetic, artificial, cultured], intended for use in jewelry [(jewelry insert)] and household products. (according to STO 45866412-16-2014 «Precious Stones. Terms and definitions)

3.2. Jewelry stones. Terms and definitions.

Corundum* (Corundum) A mineral species, a mineral of the class of oxides; having the chemical composition Al₂O₃, crystallizing in trigonal symmetry, ditrigonal-scalenohedral symmetry class (point group). (in accordance with SRT 45866412-10-2008)Natural unprocessed rubies (in raw materials). Technical specifications)

*Note: this mineral species has industrially and laboratory-produced synthetic analogues, including in the form of varieties that have no analogues in nature.

Beryl* (Beryl) A mineral species, a mineral of the silicate class, a subclass of cyclosilicates (annular silicates), having the chemical composition Be₃Al₂[Si₆O₁₈] crystallizing in hexagonal symmetry, a dihexagonal-dipyramidal symmetry class (point group). (according to SRT 45866412-16-2014 «Precious Stones. Terms and definitions)

*Note: this mineral species has industrially and laboratory-produced synthetic analogues, including in the form of varieties that have no analogues in nature.

Chrysoberyl* (Chrysoberyl) A mineral species, a mineral of the class of oxides, a subclass of complex oxides, having the chemical composition BeAl₂O₄, crystallizing in rhombic symmetry, rhombo-dipyramidal symmetry class (point group).

*Note: this mineral species has industrially and laboratory-produced synthetic analogues.

Pearls (natural)* (Pearl) A natural organogenic formation that arose inside a mollusk for reasons independent of human involvement, consisting of organic matter (mainly conchioline) and calcium carbonate (mainly aragonite). (according to SRT 45866412-16-2014 «Precious Stones. Terms and definitions)

*Note: in gemology, the concept of "pearls" with an additional definition is applied to other organogenic formations not related to the vital activity of the mollusk "elephant pearls", "bamboo pearls" and a number of others.

Axinite group* (Axinite group) A group of minerals, of the silicate class, of the sorosilicate subclass; with a common chemical composition Ca₂(Fe,Mg,Mn)Al₂B[OH|O|(Si₂O₇)₂] crystallizing in triclinic syngony.

*Note: in order to compile a gemological report (conclusion or certificate) for a piece of jewelry or an insert, the determination is made with accuracy to the group.

Amphibole supergroup* (Amphibole supergroup) A group of minerals of the silicate class, subclass inosilicates (chain and ribbon silicates). The general chemical composition of the supergroup is determined by the general formula AB₂C₅T₈O₂₂W₂ (where A = □, Na, K, Ca, Pb, Li ("□" indicates a vacancy); B = Na, Ca, Mn²⁺, Fe²⁺, Mg, Li; C = Mg, Fe²⁺, Mn²⁺, Al, Fe³⁺, Mn³⁺, Ti⁴⁺, Li; T = Si, Al, Ti⁴⁺, Be; W = (OH), F, Cl, O^2–); crystallizing in rhombic or monoclinic syngony.

*Note: minerals of this supergroup, namely groups W = (OH, F, Cl) The dominant amphiboles are rock-forming for nephrites, nephritoids and dianite.

Andalusite (Andalusite) A mineral species, a mineral of the silicate class, a subclass of non-silicates (orthosilicates); with a chemical composition determined by the formula Al₂[SiO₄]O; crystallizing in rhombic symmetry, dipyramidal symmetry class (point group).

Apatite group* (Apatite group) – a group of minerals of the phosphate class. The apatite group combines minerals with a common chemical composition determined by the formula Ca₅(PO₄)₃(F,OH,Cl) crystallizing in hexagonal symmetry, hexagonal-dipyramidal symmetry class (point group).

*Note: in order to compile a gemological report (conclusion or certificate) for a piece of jewelry or an insert, the determination is made with accuracy to the group.

Benitoite (Benitoite) A mineral species, a mineral of the silicate class, a subclass of cyclosilicates (annular silicates), with a chemical composition determined by the formula VaTi[Si₃O₉]; crystallizing in hexagonal symmetry, ditrigonal-dipyramidal symmetry class (point group). Rare.

Beryllonite (Beryllonite) A mineral species of the phosphate class, with a chemical composition determined by the formula NaBePO₄; crystallizing in monoclinic symmetry, prismatic symmetry class (point group). Rare.

Brazilianite (Brazilianite) a mineral species of the phosphate class, with a chemical composition determined by the formula NaAl₃(PO₄)₂(OH)₄, crystallizing in monoclinic symmetry, monoclinic-prismatic symmetry class (point group).

Turquoise* (Turquoise) A mineral species of the phosphate class, with a chemical composition determined by the formula CuAl₆[PO₄]₄(OH)₈•5H₂O; crystallizing in triclinic symmetry, triclinic-pinacoidal symmetry class (point group). A metacolloid cryptocrystalline aggregate is used for inserts.

*Note: this mineral species has industrially and laboratory-produced synthetic analogues.

Vesuvianite (Vesuvianite) a mineral species, a mineral of the silicate class, a subclass of sorosilicates, with a chemical composition determined by the formula (Ca,Na)₁₉(Al,Mg,Fe)₁₃(SiO₄)₁₀(Si₂O₇)₄(OH,F,O)₁₀; crystallizing in tetragonal symmetry, ditetragonal-dipyramidal symmetry class (point group).

Gagat (Gagat) rock, a kind of black coal, with a high content of bitumen; characterized by a draining texture; dense, has a bright resinous sheen, easy to polish. In Russia, the most common Siberian jet-like saprocollites, which are called jet in trade and production of decorative products.

Garnet group* (Garnet group) A group of minerals of the silicate class, a subclass of non-silicates (orthosilicates), with a chemical composition determined by the general chemical formula R₃²⁺R₂³⁺(SiO₄)₃ (where R²⁺ = Ca, Fe, Md, Mp, and R³⁺ = Al, Fe, Cr, Mn); crystallizing in cubic symmetry.

*Note: the minerals of the garnet group have industrially and laboratory-produced artificial varieties.

Grandidierite mineral species, a mineral of the silicate class, a subclass of the non-silicates (orthosilicates) subclass, with a chemical composition determined by the formula (Mg,Fe²⁺)(Al,Fe³⁺)₃(SiO₄)(BO₃)O₂; crystallizing in rhombic symmetry, rhombo-dipyramidal symmetry class (point group).

Humite group (Humite group) A group of minerals of the silicate class, a subclass of non-silicates (orthosilicates), with a common chemical composition determined by the formula nAl₂SiO₄A(F,OH)₂ (where A = Mg, Fe²⁺, Mn²⁺, Zn, Ca... and n = 1, 2, 3, 4).

Danburite (Danburite) a mineral species, a mineral of the silicate class, a subclass of tectosilicates (frame silicates), with a chemical composition determined by the formula Ca[B₂Si₂O₈], crystallizing in rhombic syngony, rhombo-dipyramidal symmetry class (point group).

Datolite (Datolite) a mineral species, a mineral of the silicate class, a subclass of orthosilicates, with a chemical composition determined by the formula Ca([SiO₄]/[BO₃(OH)]); crystallizing in monoclinic symmetry, monoclinic-prismatic symmetry class (point group).

Dianite* (Dianite) The trade name of a jeweler's stone, which is a rock of metasomatic genesis, composed of a tangled fibrous mineral aggregate of a substantially amphibole composition (with a predominance of magnesiostrontium potassium richterite over richterite and arfvedsonite) and containing an insignificant admixture (up to 2%) of potassium feldspar.

*Note: A number of researchers consider dianite as one of the varieties of jade.

Diasporas* (Diaspore) A mineral species, a mineral of the hydroxide class, with a chemical composition determined by the formula AlO(OH), crystallizing in rhombic symmetry, rhombo-dipyramidal symmetry class (point group).

*Note: this mineral species has industrially and laboratory-produced synthetic analogues.

Dioptase (Dioptase) a mineral species, a mineral of the silicate class, a subclass of cyclosilicates (annular silicates), with a chemical composition determined by the formula Si₆[Si₆O₁₈]•6H₂O; crystallizing in trigonal symmetry, trigonal rhombohedral symmetry class (point group).

Jeremejevite (Jeremejevite) a mineral species, a mineral of the borate class, with a chemical composition determined by the formula Al₆[BO₃]₅(F,OH)₃; crystallizing in hexagonal symmetry, a hexagonal-dipyramidal symmetry class (point group).

Quartz (Quartz) A mineral species, a mineral of the oxide class, with a chemical composition determined by the formula SiO2, crystallizing in a trigonal symmetry*, a trigonal trapezohedral symmetry class (point group).
The main jewelry varieties differ in color: Citrine (Citrine) – from yellow to orange; Amethyst (Amethyst) – from purple to purple; Amethyst (Ametrine) is a zonally colored quartz that combines the coloring of amethyst and citrine; Rhinestone – colorless; Smoky Quartz (Smoky Quartz) – with gray or brown coloring; Morion (Morion) – black, almost opaque variety; Prase (Prase) is a green variety of quartz, the color of which is due to the presence of inclusions; Rose quartz (Rose Quartz) is a pink variety of quartz, the color of which is due to structural defects in the crystal lattice.

*Note: for the variety (α-quartz) used for making jewelry inserts.

Kyanite (Kyanite) a mineral species, a mineral of the silicate class of the nesosilicate subclass (orthosilicates), with a chemical composition determined by the formula Al₂[SiO₄]O₄; crystallizing in triclinic symmetry, pinacoidal symmetry class (point group).

Kopal (Kopal) – fossil or modern (Natural organogenic formation see) resin of deciduous trees. Some authors classify fossil copals as mineraloids.

Coral (Coral) A natural organogenic formation, which is the skeleton material of a colony of coral polyps (class Anthozoa).

Cordierite (Cordierite) mineral species, a mineral of the silicate class, a subclass of cyclosilicates (annular silicates), with a chemical composition determined by the formula (Mg,Fe)₂Al₃[Si₅AlO₁₈], crystallizing in rhombic symmetry, rhombo-dipyramidal symmetry class (point group).

Kornerupine (Kornerupine) a mineral species, a mineral of the silicate class, a subclass of sorosilicates, with a chemical composition determined by the formula (Mg,Fe²⁺)₄Al₆(Si,Al,B)₅O₂₁(OH) crystallizing in rhombic symmetry, rhombo-dipyramidal symmetry class (point group).

Fossil bone (Fossil bone), [mammoth] Tusks (Ivory) A natural organogenic formation, which is the material of mammoth tusks, as well as other extinct animals (for example, mastodon).

Xonotlite (Xonotlite) a mineral species, a mineral of the silicate class, subclass inosilicates (chain and ribbon silicates), with a chemical composition determined by the formula Ca₆Si₆O₁₇(OH)₂, crystallizing in monoclinic symmetry, monoclinic-prismatic symmetry class (point group). Gem quality stones are rare.

Cuprite (Cuprite) A mineral species, a mineral of the oxide class, with a chemical composition determined by the formula Cu₂O; crystallizing in cubic symmetry, hexoctahedral symmetry class (point group).

Jade (Nephrite Jade) A rock of a cryptocrystalline (latent fibrous) structure, composed mainly of minerals of the amphibole group.

Nuumit (nuumit) ornamental stone, a rock, the commercial name of an iridescent variety of amphibolite, consisting mainly of amphiboles of the gedrite-anthophyllite series; synonym: ("rainbow amphibolus").

Olivine group (Olivine group) A group of minerals of the silicate class, a subclass of non-silicates (orthosilicates), with a common chemical composition determined by the formula (Mg,Fe,Mn,Ca)₂[SiO₄] crystallizing in rhombic symmetry.

Opal (Opal) A mineral species, a mineral of the oxide class, with a chemical composition determined by the formula SiO₂nH₂O. Opal has no crystalline structure and is an amorphous formation.

Pyroxene family (Pyroxene family) A family of minerals, class silicates, subclass inosilicates (chain and ribbon silicates). The pyroxene family includes two groups of minerals:

- the clinopyroxene group is a group of minerals from the pyroxene family having a chemical composition characterized by the formula (W)_1-p(X,Y)_1+p[Z₂O₆]; where: W – Na, Ca; X – Mg, Fe²⁺, Mn, Ni, Li; Y – Al, Fe³⁺, Cr, Ti; Z Si, Al; crystallizing in monoclinic symmetry, monoclinic-rhombic symmetry class (point group);

is the orthopyroxene group, a group of minerals from the pyroxene family having a chemical composition characterized by the formula X₂[Si₂O₆]; where X Mg, Fe²⁺, Mn²⁺; crystallizing in rhombic symmetry, rhombo-dipyramidal symmetry class (point group).

The pyroxenoid family (Pyroxenoid family) is a family of minerals, a class of silicates, a subclass of inosilicates (chain and ribbon silicates). The pyroxenoid family includes two groups of minerals, the structure of which involves chain silicon-oxygen radicals with a common motif [Si₅O₁₅]^5- ( [Si₅O₁₄(OH)]^5- ) – [Si₃O₉]^3- ( [Si₃O₈(OH)]^3-).

- rhodonite group;

- the wollastonite group.

Feldspar (Feldspar family) A family of minerals of the silicate class, a subclass of tectosilicates (frame silicates). Minerals of two groups of the family are used as jewelry inserts:

- alkaline (here potassium) feldspar; the group combines minerals characterized by the formation of an isomorphic series Na_xK_1-x[AlSi₃O₈]

- alkaline earth feldspar (here plagioclases); the group unites minerals characterized by the formation of a series of complete isomorphic heterovalent miscibility Na[AlSi₃O₈] Ca[Al2Si₂O₈].

Prehnite a mineral species, a mineral of the silicate class, a subclass of filosilicates (layered silicates), with a chemical composition determined by the formula Ca₂Al(Si₃Al)O₁₀(OH)₂, crystallizing in rhombic symmetry, rhombo-pyramidal symmetry class (point group).

Sillimanite A mineral species, a mineral of the silicate class, a subclass of nonsilicates (orthosilicates) with a chemical composition determined by the formula Al₂OSiO₄, crystallizing in rhombic symmetry, rhombo-dipyramidal symmetry class (point group).

Sinhalite A mineral species of the borate class, a subclass of borates with a chemical composition determined by the formula MgAlBO₄, crystallizing in rhombic symmetry, rhombo-dipyramidal symmetry class (point group). Synonym - Sinhalite.

Scapolite (Scapolite group) A group of minerals, of the silicate class, of the tectosilicate subclass (skeleton silicates), with a common chemical composition. defined by the formula (Na,Ca)₄(Si,Al)₁₂O₂₄(Cl,CO₃,SO₄) crystallizing in tetragonal syngony.

Sodalite Group A group of minerals of the silicate class, subclass tectosilicates (skeleton silicates), with a common chemical composition
X_6-n+mY_n/2[Z12O24]T₂^m-; where X –Na,K,Y– Ca, Z– Al,Be,Si, T – Cl, (SO₄), (OH), S; crystallizing in cubic, tetragonal, rhombic, monoclinic and triclinic syngony;

Taaffeite group (Taaffeite group) – a group of minerals, class of oxides, supergroup of hegbomite; whose chemical composition is characterized by the generalized formula– X₃BeY₈O₁₂, where X– Fe²⁺,Mg,Zn,Be, Y– Fe³⁺,Al. They crystallize in hexagonal and trigonal symmetry.

Topaz (Topaz) a mineral species, a mineral of the silicate class, a subclass of non-silicates (orthosilicates) with a chemical composition determined by the formula Al₂(SiO₄)(F,OH)₂, crystallizing in rhombic symmetry, in the rhombo-dipyramidal symmetry class (point group).

Tourmaline A supergroup of minerals with a tourmaline-type structure, in the class of silicates, a subclass of cyclosilicates (annular silicates), namely boron-containing silicates with an annular motif of the arrangement of silicon-oxygen tetrahedra in the structure of the crystal lattice. The chemical composition is characterized by the generalized formula XY₃Z₆(T₆O₁₈)(BO₃)₃V₃W, where:

X = Na⁺ and/or Ca²⁺, and/or K⁺, and/or vacancy;

Y = Fe²⁺ and/or Mg²⁺, and/or Mn²⁺, and/or Al³⁺, and/or Li⁺, and/or Fe³⁺, and/or Cr³⁺;

Z = Al³⁺ and/or Fe³⁺, and/or Mg²⁺, and/or Cr³⁺;

T = Si⁴⁺ and/or Al³⁺, and/or B³⁺;

O = O^2-;

B = B³⁺;

V = OH^- and/or O^2-;

W = OH^- and/or F^-, O^2-.

The minerals of the tourmaline supergroup crystallize mainly in the trigonal syngony.

* Note: Among the most common minerals (mineral type) of the supergroup used for the manufacture of jewelry inserts: elbaite, dravite, chrome-dravite, sherl, cilaisite, uvite, liddicoatite.

Phenakite A mineral species, a mineral of the silicate class, a subclass of non-silicates (orthosilicates) with a chemical composition determined by the formula Be₂[SiO₄], crystallizing in trigonal symmetry, in the trigonal rhombohedral symmetry class (point group).

Chalcedony (Chalcedony) The morphological variety of cryptocrystalline quartz is not a mineral. Varieties: agate (with a zonal color distribution), onyx (with a striped-parallel color distribution), chalcedony proper (pale-colored varieties with uniform coloring). Color varieties: carnelian-sardine (with a red tint from orange to brown), chrysoprase (green, sometimes with a slight blue tint), plasma-prasem (yellowish-green), heliotrope (dark green with red-brown spots).

Zircon A mineral species, a mineral of the class of nonsilicates (orthosilicates) with a chemical composition determined by the formula ZrSiO₄, crystallizing in tetragonal symmetry, ditetragonal-dipyramidal symmetry class (point group).

Zoisite (Zoisite) a mineral species, a mineral of the silicate class, a subclass of sorosilicates (ortho-diorthosilicates) with a chemical composition determined by the formula Ca₂Al₃(Si₂O₇)(SiO₄)O(OH) crystallizing in rhombic symmetry, rhombo-dipyramidal symmetry class (point group).

Charoite (1) a mineral species, a mineral of the silicate class, a subclass of inosilicates (chain and ribbon silicates) with a chemical composition determined by the formula

(K,Sr,Ba,Mn)_15-16(Ca,Na)₃₂[Si₆O₁₁(O,OH)₆]₂[Si₁₂O₁₈(O,OH)₁₂]₂[Si₁₇O₂₅(O,OH)₁₈]₂(OH,F)₄•3H₂O, crystallizing in monoclinic symmetry, monoclinic-prismatic symmetry class (point group).

(2) ornamental stone, rock ("charoite"). For jewelry varieties, the content of the mineral charoite is at least 90%, for jewelry and ornamental – at least 30%;

Spinel A mineral species, a mineral of the oxide class, spinel supergroup, aluminum group with a chemical composition determined by the formula mGal₂O₄, crystallizing in cubic symmetry, hexoctahedral symmetry class (point group).

Euclase A mineral species, a mineral of the silicate class, a subclass of the nesosilicate (orthosilicate) subclass, with a chemical composition determined by the formula BeAl[SiO₄](OH); crystallizing in monoclinic symmetry, monoclinic-prismatic symmetry class (point group).

Yuksporite mineral species, a mineral of the silicate class, subclass inosilicates (chain and ribbon silicates) with a chemical composition determined by the formula K₄(Ca,Na)₁₄Sr₂Mn(Ti,Nb)₄(O,OH)₄(Si₆O₁₇)₂(Si₂O₇)₃(H₂O,OH)₃, crystallizing in monoclinic syngony.

Jasper (Jasper) A metamorphogenic rock of a cryptocrystalline structure, composed mainly of quartz and chalcedony, pigmented with impurities of other minerals (epidote, amphiboles, chlorite, oxides and hydroxides of iron). In jewelry, jaspers include externally similar rocks, similar to jasper in properties and composition, but different in origin.

Amber (Amber) * fossil resin of coniferous trees. Currently, it is generally accepted to classify amber and amber-like resins as mineraloids, however, they are classified by a number of authors as minerals of organogenic origin.

3.2. Methodological definitions

3.2.1. Gemological diagnostics (of a jeweler's stone) The procedure for establishing the type (name of the gemstone, nature of origin and traces of refinement, carried out in a certain order using technical means and in accordance with regulatory documents. (according to SRT 45866412-16-2014 «Precious Stones. Terms and definitions)

3.2.2. Identification of jewelry stones The process of establishing the identity of the identified characteristics of the sample under study (here a jeweler's stone) to the main defining features of the reference sample or their description. (GOST R 51293-99 "Product identification. General provisions.»)

3.2.3. Classification of jewelry stones A system for separating jewelry stones according to quality indicators (qualitative characteristics established by standards). (according to SRT 45866412-16-2014 «Precious Stones. Terms and definitions)

3.2.4. The main classification features of a gemstone The main indicators of the quality of a gemstone (4C): weight, color, purity, cut.

• weight (weight of a jeweler's stone) The weight of a gemstone is determined in metric carats (1 carat is equivalent to 200 mg) and is one of the main classification features. (according to SRT 45866412-16-2014 «Precious Stones. Terms and definitions)
• color (gemstone color) One of the main classification features of a jeweler's stone, determined by the absence (colorless) or presence of natural coloring in a jeweler's stone, characterized by a color shade, tone and saturation, based on the property of a jeweler's stone to cause a certain visual sensation due to its spectral characteristics in the visible range of the spectrum.
• purity (purity of a jeweler's stone) One of the main classification features of jewelry stones, which determines the degree of their transparency, as well as the degree of detection, size and number of internal defects. (according to SRT 45866412-16-2014 «Precious Stones. Terms and definitions)
• cutting (gemstone cutting) One of the main classification features of faceted gemstones, characterized by a set of parameters: the type, shape and type of cut, the degree of internal reflection and the quality of processing of jewelry inserts. (according to SRT 45866412-16-2014 «Precious Stones. Terms and definitions)

3.2.5 Additional classification features of a gemstone Additional classification features of a gemstone are such optical properties and effects as:

• color changing effect the ability of a gemstone to change its color or its individual components depending on the spectral characteristics of lighting, as well as temperature, humidity and/or other external conditions;
• pleochroism the ability of a mineral to transmit (or absorb) light of certain spectral characteristics, expressed in a visual change in its color depending on a certain crystallographic direction;
• light dispersion the ability of a mineral to refract light of different wavelengths passing through it to varying degrees;
• ionization A visual effect that occurs inside a stone as a result of the reflection of incident light from the internal inhomogeneities of a mineral or rock;
  • asterism a kind of ionization, expressed in the visual effect of the appearance of a light star on the surface of a stone as a result of reflection of light from naturally located internal inclusions;
  • cat's eye effect a kind of ionization, expressed in the visual effect of the appearance of a light strip on the surface of a stone as a result of reflection of light from naturally located internal inclusions;
  • labradorescence a kind of ionization expressed in the visual effect of the rainbow play of light on the structural surfaces of a jeweler's stone, which occurs when light rays reflected from naturally oriented thin or microscopic inhomogeneities interfere;
  • adulescence a kind of ionization, expressed in the visual effect of the monochromatic play of light on the structural surfaces of a jeweler's stone (usually potassium feldspar), arising from the interference of light rays reflected from naturally oriented thin or microscopic inhomogeneities;
  • opalescence a kind of iridescence expressed in the visual effect of an iridescent or monochromatic play of light inside a jeweler's stone, resulting from the interference of light rays reflected from micro-inhomogeneities of the structural level;
  • adventurism a type of ionization expressed in a sparkling sheen resulting from the reflection of light from opaque or highly refractive internal inclusions;
• transparency the ability of a jeweler's stone to transmit directional visible light; the value is the inverse of light absorption;
• translucency the ability of a gemstone to partially transmit diffused visible light;
  the following gradations of a gemstone are distinguished by the degree of transparency and translucency:
  • Transparent; (TP)
  • translucent (Semitransparent); (STP)
  • translucent (Translucent); (TL)
  • Semitranslescent; (STL)
  • opaque (Opaque); (Oq)
• UV luminescence The ability of the stone to emit visible light when exposed to long- /short-wave ultraviolet radiation.

3.2.6. Determining the color of a jeweler's stone a sequence of actions in a complex of works carried out under specially defined conditions, aimed at determining the location of the color of a jewelry stone on the chromaticity scale, in accordance with specially selected reference samples defining the boundaries of the main intervals of color characteristics: color shade, tone, saturation. When determining the color, the results of hardware measurements can also be analyzed.

3.2.6.1. The color shade (Hue) is the component of color that distinguishes it from white, black and gray colors, which is determined by the light of the prevailing wavelengths of the visible part of the spectrum.

3.2.6.2. Tone (Tone) is a color component on the white-gray-black scale that determines the conditional amount of "lightness" ("light») or «darkness» («dark») in the coloring of a jeweler's stone.

3.2.6.3. Saturation is a color component that characterizes the purity of a color shade, which is determined by the intensity of light of the prevailing wavelengths of the visible part of the spectrum.

3.2.7. Determination of purity (jewelry stone) – the sequence of actions in the complex of works to establish the presence of significant purity characteristics in a jewelry stone and the assignment of the studied jewelry stone to the appropriate qualitative purity group in accordance with the classification of this standard.

3.2.7.1. Significant purity characteristics all detectable (visible or noticeable to the naked eye and when viewed through a 10x jewelry magnifier-triplet) purity characteristics located inside or partially inside a jeweler's stone, which include visually manifested defects that affect its transparency or uniformity of color.

3.2.7.2. Purity characteristics according to the degree of penetration into the volume of the stone are divided into:

• external defects, natural or acquired during processing, sorting, storage or transportation, located on the surface of the stone, slightly penetrating deep into the stone;
• internal defects, natural or acquired during processing, sorting, storage or transportation, located entirely inside the stone or partially coming to the surface.

3.2.7.2.1. The external characteristics of purity by origin are divided into:

• polishing lines * thin parallel lines on the surface of a faceted stone that occur during processing; (as a defect, they are relevant for stones with a purity index "slightly included" and higher)
• scratches (deep) indentation on the surface of a faceted stone in the form of a straight or curved line;
• fossa is a shallow isometric depression on the surface of the stone caused by impact, discoloration of inclusion, poor processing quality; (as a defect, they are relevant for stones with a purity index "slightly included" and higher)
• gouging (chipping) mechanical damage to the surface of the insert, accompanied by a deepening on the surface of the faces;
• tarnish (abrasion) a collection of small chips on the ribs, visually visible as whitish blurred lines;
• subgar a whitish accumulation of tiny cracks in the form of "fog" on the surface of the stone faces, resulting from excessive heating of the stone during cutting;
• fire signs near-surface cracks, which are formed as a result of thermal cracking from overheating of the stone during cutting.

3.2.7.2.2. The internal characteristics of purity by origin are divided into:

• crack a defect resulting from a violation of the integrity of the stone (splitting, cracking). There are small cracks ("cleavage"), medium-sized cracks, large ones without glare ("cracks"), as well as cracks with glare and reflective surfaces ("feather");
• inclusions (of one or more phases) material inhomogeneities inside the stone (light, colored and dark; flat and voluminous; dots, crystals, reverse crystals, tubules, needles, filamentous, grains, veils, clouds, and others);
• zoning Heterogeneity expressed in color or in some other property (optical, structural or textural). Zonality is most often caused by changes in crystallization conditions;
• cavern a cavity inside the stone, opened on the surface during cutting;
• double seam A type of structural heterogeneity that occurs at the boundary of the regular coalescence of grains (crystals) of a mineral.

3.2.7.3. Purity characteristics according to the degree of visibility by the expert are divided into:

• Very faintly noticeable inclusions and other defects, as a rule, are light, which can be easily detected by a trained expert through a 10-fold triplet jewelry magnifier upon careful examination of a jewelry stone;
• Faintly noticeable inclusions and other defects that can be detected by a trained expert with the naked eye during a careful examination of a jewelry stone;
• Noticeable inclusions and other defects that can be easily detected by a trained expert with the naked eye when examining a jewelry stone;
• Highly noticeable inclusions and other defects that an unprepared observer can easily detect upon careful examination, but which do not impair the overall perception of the stone;
• Very noticeable inclusions and other defects that an untrained observer can easily detect, which worsen the overall perception of the stone.

3.2.8. Determination of the parameters of the cut and the quality of the cut of a jewelry stone the sequence of actions in the complex of works to establish a general analysis of the result of work on the cutting of a jewelry stone, which consists of qualitative ratios of proportions, symmetry of the elements of the cut, polishing of the faceted insert of a jewelry stone. When determining the quality of a gemstone's cut, its degree of internal reflection (SVO) is taken into account.

3.2.8.1. The shape of the cut is a parameter of the cut of a jeweler's stone, determined by the geometric shape of the contour in the plane of the rundist.

3.2.8.2. Type of cut – the cut parameter of a jeweler's stone, determined by the shape of the faces and their mutual arrangement.

3.2.8.2.1. Facet cutting is divided into the following main types:

• wedge-shaped;
• stepwise;
• mixed.

3.2.8.2.2. Cabochon cut according to the type of base (pavilion) and top (crown) is divided into the following main types:

• convex (with a flat base and a convex top);
• concave (with a flat base and a concave top or a concave base and a flat top);
• double- or biconvex (with a convex base and a convex top);
• double- or biconcave (with concave base and concave top);
• convex-concave (with a concave base).

3.2.8.2.3. Stone-cutting plastic:

• cameo a kind of processing of a jeweler's stone with the execution of a carved pattern in the form of a convex relief;
• intaglio a kind of jewelry stone processing with a carved pattern in the form of a concave relief;
• small stone-cutting plastic a kind of processing of a jeweler's stone using various (mainly stone-cutting techniques) in order to give the processed product sculptural forms.

3.2.8.2.4. Combined cut is distinguished in the case of using facet and cabochon cut elements in the processing of one stone, as well as using cameo, intaglio and other small stone-cutting techniques.

3.2.8.3. The attractiveness of the cut shape is a property of the cut of a jeweler's stone, determined by the rule of the golden section and manifested in the ratio of the metric characteristics of the cut shape elements (length/width/convexity of the shape elements).

3.2.8.4. Proportions of a faceted gemstone insert The cut property of a gemstone, manifested in the ratio of the metric characteristics of the cut elements, which determines the degree of internal reflection, brilliance and play of the faceted insert of a gemstone.

3.2.8.5. Symmetry of a faceted gemstone insert A gemstone cutting property that describes a deviation from the norm in the ratio of the cut elements, differences in their metric parameters and location.

3.2.8.6. Polishing the faceted insert of a jeweler's stone A gemstone cutting property that describes the quality of the facet processing, the presence of external defects on the faces, as well as the presence or absence of traces of processing on the faces.

3.2.8.7. The degree of internal reflection (Brilliance) is a property of a gemstone cut that describes the degree of return through the corona of light reflected from the inner surface of the pavilion faces and observed from the site under standard lighting conditions.

4. Test and control methods

Before starting work on the identification of a gemstone and the classification of qualitative characteristics, for the purposes of gemological reports, all gemstones and jewelry are subject to mandatory cleaning.

All work on the identification of a gemstone and the classification of qualitative features, for the purposes of gemological reports, is carried out by at least two experts independently of each other. In case of disagreement, an additional expert is involved.

4.1. The methodology of work on the identification of a jeweler's stone.

The determination of the material of a jewelry stone for compliance with a mineral species, mineral variety, mineraloid, rock, natural organogenic formation, as well as for compliance with natural non-refined, refined, synthetic and artificial jewelry stones, cultivated organogenic formations is carried out on a single basis.

The origin of a gemstone other than natural is necessarily indicated in the name for minerals (including mineral species and varieties, mineraloids and rocks) as "Synthetic", and for organic formations "Cultured", and the fact, the type and degree of refinement – in the comments on the footnote.

4.1.1. A preliminary inspection of the jewelry insert material is carried out visually using a jewelry triplet magnifier with an increase of 10 in order to identify signs characteristic of a jewelry stone: the presence or absence of optical anisotropy, pleochroism, indirect signs of low or high hardness, cleavage, twinning, optical effects, signs indicating the origin of the stone, as well as conducting the process of gentrification.

4.1.2. At the next stage, taking into account the result obtained during the preliminary examination, the determination is performed by hardware diagnostic methods using a tester for determining colored stones (based on determining the thermal conductivity property), determining the refractive index (using a refractometer or reflectometer), studying UV luminescence (visually and using electron spectroscopy).

4.1.3. After fulfilling the requirements of paragraphs 4.1.1., 4.1.2., a microscopic examination of the jewelry stone is performed, including in an immersion medium, including the study of the appearance of internal inclusions, optical inhomogeneities, color zonality, fluorescence zonality, determination of the presence of substances unusual for natural stone (inclusions and/or fillers).

4.1.4. Upon receipt of the results of the inspection according to paragraph 4.1.3. a complex of spectral studies is carried out, aiming to confirm the fact of determining a jeweler's stone at the spectral level, identify possible refinement, confirm the determination of origin (natural or synthetic).

4.2. Methods of work on the classification of jewelry stone.

The determination of the qualitative characteristics of natural jewelry stones that have not been refined, subjected to refinement, as well as synthetic (cultured) and artificial ones is carried out on a single basis. The origin of the gemstone (other than natural) is necessarily indicated in the name, and the fact, type and degree of refinement are indicated in the comments on the footnote. If the determination of the nature of the origin or the fact of the presence of gentrification is difficult to fix, then such a fact must be indicated in the comments (to the description of the insert) or in the note (to the gemological report).

4.2.1. Classification of a gemstone by weight.

The weight of a gemstone is one of its most important evaluation characteristics.

4.2.1.1. For the purposes of correct compilation of gemological reports, the following categories of jewelry stones are distinguished by weight:

• Small – weighing up to 1.00 ct.;
• Medium-sized – with a mass from 1.00 ct inclusive to 5.00 ct.;
• Large – with a mass of over 5.00 ct inclusive.

4.2.1.2. The mass of an unfixed gemstone is determined by weighing the stone on an analytical scale of at least accuracy class III.

4.2.1.3. The mass of the jeweler's stone installed in the product is determined by calculation. All measurements are made with a micrometer device of the "Leveridge" type, and if the stone is unavailable for measurement, the linear dimensions are determined using a measuring magnifier with a resolution of 10X and a scale division of at least 0.1 mm. The error in determining the mass of the stone available for standard measurements and inspection does not exceed 5%. With limited access to the stone or the absence of the possibility of removing dimensional indicators, the size of the stone is determined taking into account standard ratios and proportions, and indirect signs indicating the magnitude of such ratios and proportions are also taken into account. In this case, the error in determining the mass of the stone does not exceed 15%.

Note: if a jeweler's stone is found in a blind fixation in the product and low cut quality indicators, the error can reach 25% (for such stones, it is suggested in gemological reports to indicate the linear dimensions available for measurement and not to indicate the calculated weight).

4.2.1.4. The weight of a gemstone, in the gemological report, is expressed in hundredths of a carat.

4.2.1.5. When reflecting the mass in the gemological report, the rule of rounding the third nine is used (for example, if the weight of the stone is 0.999 ct, then the size of 1.00 ct will be indicated in the gemological report.).

4.2.2. Classification of jewelry stone by color.

4.2.2.1. The color of a gemstone for the purposes of a gemological report is characterized by a general description of a variety of spectral color, and the color classification is determined by a three-component combination of color shade, tone and saturation.

4.2.2.2. Description of the color shade (Hue) It is based on the characteristic of the main spectral color with a description of the additionally present transitional color in accordance with the gemstone color assessment system developed by the Gemological Institute of America (GIA) based on the Mansel color system. To determine the color shade, a set of chromaticity standards "GIA GemSet" and/or atlas "Munsell Book of Color" is used. (see Table 1.)

4.2.2.3. The description of the tone is based on a characteristic that determines the conditional amount of "lightness" ("light") or «darkness» («dark») in the coloring of a gemstone in accordance with the gemstone color assessment system developed by the Gemological Institute of America (GIA) based on the Mansel color system. To determine the tone characteristic, a set of chromaticity standards "GIA GemSet" and/or atlas "Munsell Book of Color" is used. (see Table 2.)

4.2.2.4. The Saturation description is based on a characteristic that determines the conditional number of color components characterizing the purity of the color shade, which is determined by the intensity of light of the prevailing wavelengths of the visible part of the spectrum in the coloring of a gemstone in accordance with the gemstone color assessment system developed by the Gemological Institute of America (GIA) based on the Mansel color system. A set of chromaticity standards "GIA GemSet" is used to determine the saturation characteristic; and/or the atlas "Munsell Book of Color". (see Table 3.)

4.2.2.5. Stones with achromatic coloring are characterized by a description of the color shade (for gray and brown colors, with the addition of a description of the tone component):

• white – for the white primary color;
• black – for the black base color;
• gray for gray;
• brown is for brown;
• colorless – for colorless stones.

For brown and gray achromatic colors, in the presence of a slightly noticeable shade, a color shade characteristic can be added: pinkish- (pinkish-), yellowish- (yellowish-), greenish- (greenish-), bluish- (bluish-), violetish- (purple-), purplish (purplish-).

Table 1. Description of the component of the Hue of jewelry stones.

Table 2. Description of the tone component ("Tone") of gemstones.

Table 3. Description of the color saturation component ("Saturation") of gemstones.

* The term «Pink» is used for colors with a predominance of the primary spectral color «Red»:

«Red » tone/saturation – 1-4/1-4, 5/1-2, 3/5;

«reddish Purple » tone/saturation – 1-4/1-5;

«Red-Purple or Purple-Red » tone/saturation – 1-5/1-6;

«strongly purplish Red » tone/saturation – 1-5/1-3, 3-4/3-4;

« slightly purplish Red » tone/saturation – 1-4/1-4, 3/5;

« orangy Red » tone/saturation – 1-3/1-3;

« Red-Orange or Orange-Red » tone/saturation – 1-5/1-2, 1-3/3.

** The term «Brown» is used for colors in the range of primary spectral colors from «Orange» to «Yellow» ("Yellow"):

"Orange" tone/saturation – 1-8/1-3;

«yellowish Orange» tone/saturation – 1-8/1-3;

«orangy Yellow» tone/saturation – 1-8/1-3;

«Yellow» tone/saturation – 1-8/1-3.

4.2.2.6. The color is determined on a neutral white background, under standard artificial light conditions equivalent to northern daylight (at the equinox at 48° north latitude). For these purposes, the D65 illuminant is used (according to the classification of the International Commission on Illumination - CIE). In this case, the assessed sample of the gemstone is placed on a V-shaped field with the crown facing up, and the stone is inspected perpendicular to the platform.*

* When determining the color in accordance with other evaluation systems, the viewing conditions stipulated by the rules of the evaluation system are provided.

4.2.2.7. When determining the color, after conducting a visual (organoleptic) comparison with the reference sample, the results of instrumental measurements can be taken into account.

4.2.2.8. For uncut gemstones (not set and in products), as well as for cut gemstones in a setting that makes it difficult to determine the color with the error specified by the standard, only the color shade component is assessed.

4.2.2.9. For stones with a generally accepted commercial name of color established on the basis of standard color characteristics (provided for by the classification of the International Commission on Illumination - CIE) and additional conditions for the use of the term, it is possible to indicate the generally accepted commercial name of color.

4.2.3. Classification of gemstones by clarity.

4.2.3.1. Determination of the clarity of a gemstone for the purposes of compiling a gemological report is made with the naked eye using an arbitration viewing device (a standard triplet jeweler's loupe with 10x magnification), against a neutral white background, in conditions of standard artificial light equivalent to northern daylight (under conditions of the equinox at 48° north latitude). For these purposes, a D65 light source is used (according to the classification of the International Commission on Illumination - CIE).

4.2.3.2. To perform a set of works to determine the purity of a jewelry stone, the following sequence of determining the purity factors is provided:

• quantity;
• size;
• contrast;
• type;
• location.

4.2.3.3. The clarity characteristics of a gemstone are revealed when examining the stone in the following order:

• table;
• middle zone (upper wedges and main facet of the crown);
• peripheral zone (lower wedges of the crown)
• girdle;
• pavilion.

After identifying the clarity factors, their overall impact on the clarity of the gemstone is assessed. When evaluating gemstones of boundary clarity groups, it is recommended to compare them with a reference sample that sets the lower limit for a given group.

4.2.3.4. For the purposes of classifying transparent gemstones by clarity, the following procedure for determining the quality group by clarity is adopted:

4.2.3.4.1. Clarity group "Loupe clean" (LC) MGC - without defects, defects (hereinafter - Clarity quality factors) are insignificant, not detectable under a 10x magnifying glass;

4.2.3.4.2. Clarity group "Eye clean" (EC) MGC - clarity quality factors that are very slightly noticeable (point or superficial), not detectable when viewed with the naked eye through the crown of the stone, can be detected when viewed through a standard triplet magnifying glass with a magnification of 10^x times.

For emeralds, red beryls and “arburz” tourmalines, several individual inclusions noticeable to the naked eye in the peripheral zone are allowed.

Clarity quality factors: points, stripes, tiny cracks (“cleavage”), weakly expressed color zoning noticeable from the pavilion side.

4.2.3.4.3. Clarity group “slightly included” (SI) MGC – clarity quality factors that are barely noticeable to the naked eye in the middle and peripheral zones; isolated, slightly noticeable defects in the central zone are allowed.

For beryls, chrysoberyls, spodumenes, blue and colorless topazes, green tourmalines, zoisites (in particular, tanzanite), colorless and blue zircons, significant clarity characteristics are isolated, slightly noticeable defects in the volume of the stone.

For emeralds, red beryls and "arburz" tourmalines may contain several individual inclusions visible to the naked eye in the central zone, as well as small areas with slight loss of transparency in the peripheral zone.

Clarity quality factors: dots, stripes, included crystal, multiphase inclusions, needle-like and filiform inclusions, veils, cracks, color zoning very weakly visible through the crown.

4.2.3.4.4. Moderately included (MI) Clarity Group - clarity quality factors visible to the naked eye in the bulk of the stone and in the peripheral zone, areas with partial slight loss of transparency are allowed.

For beryls, chrysoberyls, spodumenes, blue and colorless topazes, green tourmalines, zoisites (in particular - tanzanite), colorless and blue zircons, significant clarity characteristics are moderately noticeable defects in the bulk of the stone.

For emeralds, red beryls and “arburz” tourmalines are allowed to have moderately visible inclusions with partial noticeable loss of transparency (including weak in the central zone).

Quality factors of clarity: dots, stripes, included crystal, multiphase inclusions, needle-like and filiform inclusions, veils, cracks ("cleavage", "cracks", "feather"), clouds, color zoning noticeable through the crown.

4.2.3.4.5. The "Heavily included" (HI) clarity group is the clarity quality factors that are highly visible to the naked eye in the bulk of the stone; areas with partial loss of transparency (including in the central zone) are allowed.

For beryls, chrysoberyls, spodumenes, blue and colorless topazes, green tourmalines, zoisites (in particular, tanzanite), colorless and blue zircons, significant clarity characteristics are highly visible defects in the bulk of the stone with partial loss of transparency (including weak loss in the central zone).

For emeralds, red beryls and "arburz" tourmalines are allowed to have condensations of inclusions that are very noticeable to the naked eye with a significant loss of transparency in the volume of the stone.

Quality factors of clarity: dots, stripes, included crystal, multiphase inclusions, needle-like and filiform inclusions, veils, cracks ("cleavage", "cracks"), cloud, very pronounced color zoning.

4.2.3.5. For stones with clarity characteristics lower than "Heavily included", clarity gradations are not determined.

4.2.3.6. To classify stones of varying degrees of opacity (translucent, opaque), the quality characteristics of clarity are determined based on external clarity factors (cracks, caverns, chips, mineral and other inclusions).

4.2.3.6.1. Clarity group “Lope clean” (LC) MGC - without defects, clarity quality factors are insignificant, not detectable when viewed under a 10x magnifying glass;

4.2.3.6.2. Clarity group “eye clean” (EC) MGC - very subtle (point or superficial) purity quality factors, not detectable with the naked eye, can be detected when viewed through a standard triplet magnifying glass with a magnification of 10^x times.

Quality factors of purity: points, stripes, tiny cracks ("cleavage"), very weakly expressed color zoning.

4.2.3.6.3. Clearness group "slightly included" (SI) MGC – clarity quality factors that are barely noticeable to the naked eye in the middle and peripheral zones, isolated barely noticeable defects in the central zone are allowed.

Clarity quality factors: dots, stripes, included crystal, needle-like and filiform inclusions, cracks ("cleavage", "cracks"), very little noticeable through the crown color zoning or structural heterogeneity.

4.2.3.6.4. "moderately included" (MI) clarity group MGC – clarity quality factors visible to the naked eye in the peripheral zone, areas with partial heterogeneity are allowed.

Clarity quality factors: dots, stripes, included crystal, needle-like and filiform inclusions, veils, cracks ("cleavage", "cracks", "feather"), clouds, color zoning or structural heterogeneity visible through the crown.

4.2.3.6.5. Clarity group "Heavily included" (HI) MGC – clarity quality factors highly visible to the naked eye in the bulk of the stone, areas with heterogeneity (including in the central zone) are allowed.

Clarity quality factors: dots, streaks, included crystal, needle-like and filiform inclusions, veils, cracks, very pronounced color zoning or structural heterogeneity.

4.2.3.7. To determine the clarity of an unmounted stone with clarity characteristics of “eye clean” (EC) MGC and higher, a binocular microscope (with magnification up to 40x) is used as an arbitration control tool.

4.2.3.8. For a stone mounted in a frame, depending on the type of setting, clarity characteristics higher than “slightly included” (SI) MGC are not set.

4.2.3.9. For faceted gemstones with chips that potentially affect the integrity of the stone, as well as with chips and scratches that noticeably affect the appearance of the stone, the clarity parameter – “Heavily included” (HI) MGC is determined by default.

4.2.3.10. For uncut gemstones in products, for tumbled stones, as well as faceted gemstones with chips in the form of loss of 1 or more facets (and for cabochons - from 15% of the surface or more) - clarity parameters are not determined.

4.2.4. Classification of gemstones by cut quality.

4.2.4.1. The cut quality of gemstones is determined only when the stones are provided for examination in an unmounted form (at the customer's request). For gemstones set in jewelry, the quality characteristics of the cut are not determined.

4.2.4.2. When determining the cut quality of a faceted gemstone, the following parameters are assessed:

• Shape balance - the ratio of the elements of the shape of the cut stone, their proportions that determine the appearance of the stone, the degree of internal reflection, and the characteristics of the stone's shine.
• Polishing - the quality of the surface treatment of the facets (and girdle) of a gemstone, affecting its appearance and brilliance.
• Brilliance, or more precisely the degree of internal reflection (DIR) is a parameter that indirectly results from the assessment of the cut based on proportions, symmetry and polish.

4.2.4.2.1. Shape balance is an indicator consisting of an assessment of the balance of the outline (attractiveness of the shape, proportions, symmetry) and the balance of the profile (attractiveness of the shape, proportions, symmetry):

• Shape attractiveness is the ratio of the shape elements of a faceted gemstone (length/width/convexity of the cut shape elements), which determines the appearance (shape balance) of the stone. The ratio of linear dimensions in assessing the attractiveness of a shape is determined by the "golden section" rule;
• Proportions are the relationship of the main elements of a gemstone's cut, determining the appearance (balance of the shape of the stone) and the degree of internal reflection.
• Symmetry is a property that describes the deviation from the norm of various elements of the cut and their placement, affecting the appearance (balance of the shape of the stone) and the features of the shine of the gemstone. Symmetry is expressed in the regular arrangement and repetition of the cut elements, their geometric identity and correspondence to the ideal form.

4.2.4.2.2. Polishing is an indicator consisting of an assessment of the degree of visibility of defects in the processing (polishing) of the stone or their absence, as well as acquired external defects that can be eliminated by re-polishing, if this does not lead to a significant decrease in weight.

4.2.4.2.3. Brilliance (SVO) is a parameter that indirectly results from the assessment of the cut by proportions, symmetry and polishing. The degree of internal reflection (DIR) is defined as the ratio of the sum of the projections of the areas of all light-reflecting pavilion facets to the total surface area of ​​the projections of the pavilion facets (reflective + transmitting + absorbing) onto the girdle plane.

4.2.4.3. Additional parameters for assessing the cutting quality of a faceted gemstone;

4.2.4.3.1. Window - a parameter that determines the percentage of pavilion facets in the projection onto the girdle area that are transparent for viewing from the table. The window reduces the degree of internal reflection (DIR) and can also affect the assessment of the color of the stone.

4.2.4.3.2. Extinction - a parameter that determines the percentage ratio of pavilion facets projected onto the girdle area that are not transparent to view from the platform and do not reflect light. Extinction may affect the assessment of the stone's color indicators.

4.2.4.4. When determining the quality characteristics of a gemstone's cut, the main means of determining and controlling proportions is the organoleptic method using a measuring magnifying glass (with a magnification of 10^x times) and tilt angle palettes. A shadow proportionoscope may be used as an additional control tool.

4.2.4.5. When controlling linear dimensions and proportions, the "Leveridge" electronic micrometer measuring device is used as an additional control tool. and a measuring magnifying glass (with a magnification of 10^x and a calibrated ruler with a division value of 0.1 mm). A shadow proportionoscope can be used as an additional means of control.

4.2.4.6. Evaluation of the attractiveness of the cut of a gemstone:

• in relation to linear dimensions is carried out in accordance with the parameters given in Table 4;
• in terms of the expression of individual elements of the cut, is carried out in accordance with the parameters given in Table 5.

Table 4. Evaluation of the attractiveness of the contour shape by linear dimensions.

Table 5. Evaluation of the attractiveness of the outline shape from the table side by the elements of the cut.

4.2.4.7. When assessing the proportions of a faceted gemstone, the following cutting parameters are taken into account:

• Linear dimensions of the cut (total height in % of the width);
• Table size;
• Main angle of inclination of the crown;
• Main angle of inclination of the pavilion;
• Ratio of the height of the crown to the depth of the pavilion;
• Girdle thickness;
• Size of the culet (keel, spike).

4.2.4.8. When assessing the proportions of a cabochon gemstone, the following cutting parameters are taken into account:

• Linear dimensions of the cut (total height in % of width);
• Main angle of inclination of the crown;
• Main angle of inclination of the pavilion;
• Ratio of the height of the crown to the depth of the pavilion (in convex-convex cabochons)
• Girdle thickness;

4.2.4.9. The assessment of the proportions of the cut of a gemstone is made in accordance with the parameters given in Tables 6 and 7.

Table 6. Assessment of the proportions of the cut of a faceted gemstone.

Table 7. Evaluation of the cut proportions of a cabochon gemstone.

4.2.4.10. The symmetry and polishing quality of jewelry stones is assessed with the naked eye. A 10x triplet jewelry loupe and a 10x measuring loupe with a calibrated ruler with a division value of 0.1 mm are used as an arbitration viewing tool.

4.2.4.11. When assessing the symmetry of faceted gemstones, the following factors are taken into account:

Shape symmetry:

• asymmetry of the girdle contour in plan (deviation from the ideal shape, unequal arcs, unequal lobes, unequal wings, unequal shoulders);
• non-parallel arrangement of the plane of the table relative to the plane of the girdle;
• shifting the center of the table relative to the center of the girdle contour;
• shifting the center of the culet relative to the center of the cut (girdle contour);
• the girdle line is not forms a plane (wavy girdle);
• unequal crown convexity;
• unequal pavilion convexity;
• excessive pavilion convexity;

Symmetry of cutting elements:

• irregular facet shape;
• violation of facet identity;
• irregular arrangement of facet junctions;
• slanted culet (relative to the girdle plane);
• disproportionately elongated culet;
• uneven girdle height;
• displacement of crown facets relative to pavilion facets;
• non-convergence of edges to a point;

4.2.4.12. When assessing the symmetry of cabochon gemstones, the following factors are taken into account:

Symmetry of shape:

• asymmetry of the girdle contour in plan (deviation from the ideal shape, unequal arcs, unequal lobes, unequal wings, unequal shoulders);
• shifting of the crown center relative to the cutting center (girdle contour);
• shifting of the pavilion center relative to the cutting center (girdle contour);
• the girdle line does not form a plane (wavy girdle);
• unequal convexity of the crown;
• unequal convexity of the pavilion;
• excessive convexity of the crown;
• excessive pavilion convexity;

4.2.4.13. The symmetry of a gemstone is assessed in accordance with the parameters given in Table 8.

Table 8. Assessment of the symmetry of the cut of a faceted gemstone.

4.2.4.14. When assessing the polishing of jewelry stones, the following factors are taken into account:

• polishing marks;
• chips that do not noticeably affect the integrity of the stone or individual cutting elements;
• chips and scratches that do not noticeably affect the appearance of the stone;
• abrasion of peaks, edges and facets;
• underpolishing of the surface, expressed in dullness, roughness, the presence of pits, growth forms;

4.2.4.15. The symmetry of a gemstone is assessed in accordance with the parameters given in Table 9.

Table 9. Assessment of polishing of a faceted gemstone.

4.2.3.1. The brilliance (SBO) of a faceted gemstone for the purpose of assessing the quality of the gemstone's cut is determined with the naked eye using an arbitration viewing device (a standard triplet jeweler's loupe with 10x magnification), on a neutral white background, under standard artificial light conditions equivalent to northern daylight (under equinox conditions at 48° north latitude). For these purposes, the D65 illuminant is used (according to the classification of the International Commission on Illumination - CIE). In this case, the degree of manifestation of the internal reflection effect is observed from the side of the crown, in a position of the platform close to perpendicular to the observation line.

4.2.4.16. The gloss assessment (GVA) of a faceted gemstone is performed in accordance with the parameters given in Table 10.

Table 10. Gloss assessment (degree of internal reflection - GVA) of a faceted gemstone.

4.2.4.17. The overall assessment of the quality of cutting of gemstones is based on the average value reflecting the proportionality, symmetry, polishing quality and brilliance (SBO) of the cut stone in accordance with the parameters given in Tables 11 and 12.

Table 11. Comprehensive assessment of the influence of proportions, symmetry and polishing.

Table 12. Evaluation of the quality of cut of transparent faceted gemstones taking into account the comprehensive assessment of the influence of proportions, symmetry and polishing on the brilliance assessment (SBO).

5. Contents of the gemological report (conclusion or certificate).

5.1. General Provisions

5.1.1. Gemological reports on laboratory tests submitted for the study of gemstones in products or in unmounted form are issued on the basis of a set of works on the study of the gemstone in the form of gemological reports and/or certificates of conformity.

5.1.2. Gemological reports provide information about the gemstone, its origin, the presence of treatment (if any) and its type, weight and size of the gemstone. In addition, at the client's request, the expert opinion may provide information on the quality characteristics of the gemstone.

5.1.2.1. Information on the gemstone in gemological reports is provided in the form of the final research result.

5.1.2.2. Information on the quality characteristics of the gemstone is provided in accordance with the requirements of the organization's standard "STO MGC-2016/3". At the customer's request, the comments may include the quality characteristics of the gemstone in accordance with other standards in force in the Russian Federation.

5.1.2.3. When issuing a gemological report on a piece of jewelry with a gemstone, in addition to information on the origin, type of treatment, weight, size, color, transparency of the gemstone(s) and other inserts (if any), information on the type of jewelry and its weight is provided. The gemological report also includes an indication of the value of the sample stamped on the product (without identifying information on the hallmark). At the customer's request, qualitative gradations of color and purity assessment of a gemstone may be specified.

5.1.3. When issuing a gemological certificate, information is provided on the conformity of the gemstone with the requirements of this standard (in accordance with the voluntary certification system of the Moscow Gemological Center), namely: its origin, the presence of treatment (if any) and its type, weight and size, its qualitative characteristics - color, purity, and the resulting assessment of the quality of the cut (in accordance with the requirements of this standard). At the client's request, the luster assessment (LLA) can be allocated separately.

5.1.3.1. Information about the gemstone in gemological certificates is provided in the form of the final research result.

5.1.3.2. Work on the voluntary certification procedure and the issuance of a certificate is carried out on the basis of a written request from the client and the execution of an agreement on the provision of services for the voluntary certification procedure.

5.1.3.3. When issuing a gemological certificate for a piece of jewelry, in addition to information about the origin, type of treatment, weight, size, color, transparency of the gemstone (stones) and other inserts (if any), information about the type of jewelry and its weight is provided. The gemological report also contains an indication of the value of the sample affixed to the product (without identifying information about the hallmark).

5.1.4. Gemstones and jewelry with gemstones for the purposes of compiling gemological reports are accepted only in a pre-prepared form, namely:

• gemstones and jewelry must be without tags, stickers and similar attributes that change the weight of the product;
• gemstones and jewelry must be thoroughly washed and dried.
• items and jewelry with contaminated surfaces are not allowed to be accepted for the purposes of compiling gemological reports.

5.2. Disclosure of information

5.2.1. A full-length gemological report on laboratory tests of a gemstone submitted for testing in unmounted form contains the following information:

• Series and Number of the gemological report;
• Date of the test;
• Name of the mineral type (Mineral type) of the gemstone, if artificial or synthetic origin is detected, if the stone is synthetic or artificial – the indication “Synthetic / Artificial” is mandatory before the name of the mineral type;
• Name of the mineral variety (Mineral variety) (for example: Emerald, Ruby, Sapphire), if synthetic origin is detected, the indication "Synthetic / Artificial" before the name of the mineral variety is mandatory;
• if refinement is detected, the fact of the presence of signs of refinement, as well as the type of refinement, are indicated in the comments;
• Type of cut (Shape and Cutting Style);
• Weight;
• Linear dimensions (Measurements);
• Color (Color Hue);
• Color gradation (Color Grade) is indicated in certificates without fail for stones weighing from 1.0 carat, for smaller stones and in the conclusion - at the customer's request;
• Transparency;
• Clarity Grade is indicated in certificates for gemstones without fail for stones weighing 1.0 carats or more, and in reports for smaller stones - at the customer's request;
• Cut Grade is indicated in certificates for gemstones without fail for stones weighing 1.0 carats or more, and in reports for smaller stones - at the customer's request; as an additional characteristic of the cut, at the customer's request, the brilliance rating (SVO) can be indicated.
• Fluorescence rating;
• Notes (if necessary);
• Photograph of the gemstone;
• Identity diagram (Plotting) can be provided if necessary, while the preparation of the diagram is issued as a separate service;
• Link to the official website of the organization.

5.2.2. A full-length gemological report on laboratory studies of the gemstone installed in the jewelry item submitted for study contains the following information:

• Series and Number of the Gemological Report;
• Date of the Study;
• Name of the Jewelry;
• Name of the Mineral Type of the Jewelry Stone, if artificial or synthetic origin is detected, if the stone is synthetic or artificial - it is mandatory to indicate “Synthetic / Artificial” before the name of the mineral type;
• Name of the Mineral Variety (for example: Emerald, Ruby, Sapphire), if synthetic origin is detected, it is mandatory to indicate “Synthetic / Artificial” before the name of the mineral variety;
• if refinement is detected, the comments indicate the fact of the presence of signs of refinement, as well as the type of refinement;
• if there is a limitation on the possibilities or impossibility of conducting research to identify refinement or the nature of the origin of the insert for objective reasons (for example, a setting that does not allow the stone to be studied for its origin), the report includes a corresponding comment - "determination of the nature of origin (refining, quality characteristics) was carried out without removing it from the setting" or “the nature of origin (treatment, quality characteristics) was not determined”.
• Shape and Cutting Style;
• Linear Dimensions* (Measurements);
  *Note: In jewelry certificates, the linear dimensions column for stones smaller than 4.0 mm indicates intervals corresponding to the average size in the stone grading or the standard estimated weight (at the customer's request).
• Approximated Carat Weight;
• Color Hue;
• Color Grade is indicated in certificates – mandatory for stones over 1.0 carats;
• Transparency;
• Clarity Grade is indicated in gemstone certificates mandatory for stones over 1.0 carats;
• Notes (if necessary);
• Jewelry weight;
• Indication of the sample value (if necessary);
• Photograph of the jewelry;
• Link to the official website of the organization.

5.2.3. In gemological reports on laboratory tests submitted for the study of gemstones in products or in an unattached form in the name of the report or the name of the insert ("Mineral type" / “Mineral variety”) indicates only the mineral type and mineral variety for a natural gemstone and “Synthetic / Artificial” before “Mineral type” / “Mineral variety” for a gemstone of synthetic origin.

5.2.4. In gemological reports on laboratory tests submitted for the study of gemstones in products or in loose form for a natural (as well as for an artificial or synthetic) gemstone that has undergone a refining process, the identified refining process must be indicated in the notes or footnotes.

5.2.5. In gemological reports on laboratory tests submitted for the study of gemstones in products or in unmounted form, if it is impossible to conduct tests to establish the fact of refinement of a natural (as well as synthetic or artificial) gemstone, the notes, respectively, footnote, must indicate that the fact of refinement was not established.

5.2.6. In gemological reports on laboratory tests submitted for the study of gemstones in products, if it is impossible to establish the mass of a gemstone by direct weighing, its mass is determined by a calculation method in accordance with empirical formulas for calculating the weight of gemstones with the introduction of appropriate adjustments for the deviation of the cut from the "ideal".

5.2.7. All issued gemological reports are available for online verification on the official website of the organization - mgc-labs.ru.

5.2.8. This standard of the organization is publicly available on the official website of the organization.

5.2. Tolerances

5.2.1. When determining the mass of an unmounted gemstone, its weight is determined to one thousandth of a carat with an error of ±0.001 ct. In the conclusion, the weight is given in full hundredths of a carat. An exception is the rounding rule for the third nine after the decimal point. Thus, the weight of a 0.998 carat gemstone will be indicated as 0.99 ct., and the weight of a 0.999 carat gemstone will be reflected as 1.00 ct.

5.2.2. When calculating the mass of a standard-cut gemstone installed in a product, depending on the degree of limitation of viewing the cutting elements, an error of up to 5% is allowed.

5.2.3. When calculating the mass of a gemstone installed in a product that has a shape and type of cut other than a standard cut, depending on the degree of limitation of viewing the cutting elements, an error of up to 15% is allowed.

5.2.4. When determining the linear dimensions of a gemstone in a jewelry product, the linear dimensions are given in whole tenths of a millimeter. The error in measuring the linear dimensions of the insert in the jewelry item is allowed up to 5%.

5.2.5. When determining the linear dimensions of a gemstone in a jewelry item, in the absence of the possibility of direct measurement of the linear dimensions, the determination of such parameters for calculation is made on the basis of the preferred proportions of the gemstone of the corresponding type of cut, taking into account the deviations in the geometry of the insert.

5.2.6. When determining the mass of a jewelry item with gemstones for the preparation of a gemological report, its weight is determined to one thousandth of a gram with an error of ±0.001 g. The conclusion provides the weight of the jewelry item in full hundredths of a gram.

5.2.7. When determining the quality characteristics of jewelry stones installed in a jewelry item, a deviation from those in an unfixed form of up to 1-2 gradations is allowed, depending on the nature of the setting.

5.3. Limitations

5.3.1. Standard of the organization "Moscow Gemological Center" (hereinafter referred to as STO MGC) is not an industry document or a national standard.

5.3.2. All gemological reports (conclusions, certificates) are provided exclusively at the voluntary request of the client (an individual or legal entity).

5.3.3. All characteristics determined in accordance with the STO MGC and specified in gemological reports (conclusions, certificates) should be considered only in connection with international, industry and national standards.

5.3.4. MGC LLC (Moscow Gemological Center) shall not be liable (legal, economic or any other types of liability) for lost profits, reputational losses or other damage that may be caused in connection with the use of the MGC gemological report.

5.3.5. Each gemological report (conclusion, certificate) is provided exclusively for a gemstone or jewelry item. MGC LLC (Moscow Gemological Center) shall not be held liable (legal, economic or any other types of liability) for subsequent full or partial substitution of the subject, examination after the issuance of the gemological report.

5.3.6. Each gemological report (conclusion, certificate) is current at the time of issue, determined by the technical, methodological and legislative conditions for conducting research and testing, as well as registration and issuance.

5.3.7. MGC LLC (Moscow Gemological Center) shall not be held liable (legal, economic or any other types of liability) for the unlawful use of MGC conclusions and certificates.

5.3.8. MGC (MGC) is an officially registered trademark protected by the copyright holder in the territory of the Russian Federation. Reproduction of this gemological report (conclusion or certificate), or any part of it (except for the original issued to a specific client), without the written consent of the MGC is prohibited.

Note to the Standard of the Organization "Moscow Gemological Center" STO MGC "Natural Jewelry Stones".

Types of refinement of gemstones other than diamonds (processing for the purpose of visual improvement of quality characteristics) and their abbreviations for the purposes of compiling gemological reports.

 

Types of stone finishing	Purpose of finishing	Symbol
Glass Filling	Filling of open cracks and pores, as well as caverns (cavities) with highly refractive amorphous inorganic compounds (glass) in order to mask cracks and cavities. According to the effect of filling on improving the quality characteristics of the stone, three degrees of intensity are distinguished: GF1 - minor effect; GF2 - moderate effect; GF3 - strong influence.	GF
Filling with polymers, as well as unidentified materials (Filling)	Filling cracks and pores, as well as caverns (cavities) with amorphous organic and other compounds in order to mask internal and surface defects. According to the influence of filling on improving the quality characteristics of the stone, three degrees of intensity are distinguished: F1 - minor influence; F2 - moderate influence; F3 - strong influence.	F
Filling cracks with oils (Oil/Resin)	Filling cracks in jewelry and ornamental stones with oils (mainly of plant origin) to mask cracks and pores.	O
Waxing	Surface treatment of stones with wax, paraffin or similar materials in order to mask open surface cavities	W
Impregnation with organic substances	Impregnation of jewelry and jewelry-and-ornamental stones with colorless organic substances (except glass) in order to change the qualitative characteristics of color and/or purity, and/or transparency	I
Bleaching	Brightening of the natural color of the stone by  chemical reagents and/or electromagnetic radiation.	B
Dyeing	Dyeing of a gemstone along cracks and pores in order to change the color characteristics with various foreign substances.	D
Colore Glass Filling	Filling open cracks and pores with highly refractive amorphous mixtures with a dye admixture in order to mask cracks and change color characteristics.	CG
Surface coloring (Coating)	Surface coloring by applying coloring compositions, building up mineral films and other methods of changing the color of a jewelry stone with foreign dyes in order to change color characteristics.	C
Heat treatment (Heating)	Heat treatment of a gemstone to change its color and/or clarity characteristics, as well as in combination with other types of treatment. By the effect of heat treatment on changes in composition, preservation of internal inclusions and quality characteristics of the stone, six degrees of intensity are distinguished: Н 1 - minor effect (visually indistinguishable); Н 2 - minor effect (without destruction of internal inclusions); Н 3 - moderate effect (partial destruction of internal inclusions is noted); Н 4 - strong influence (internal inclusions are destroyed); Н 5 - very strong influence (dissolution of inclusions, partial melting); Н 6 - outstanding influence (relics of some inclusions, complete remelting). Without specifying the degree of heat treatment, the index – is used. TE	H (TE)
Radiation treatment (Irradiation)	Radiation treatment of a gemstone to change its color characteristics	R
High-temperature treatment in an environment with a coloring reagent (Diffusion)	High-temperature treatment of a gemstone in a medium with a coloring reagent to change the color characteristics.	U
High-temperature treatment (for corundum) in a medium with beryllium compounds (Be-Diffusion)	High-temperature treatment (for jewelry varieties of corundum) in a medium with beryllium compounds to change the color characteristics.	Be-Dif
High-temperature treatment in a medium with a flux component (Flux treatment)	High-temperature treatment in a flux-containing environment for the purpose of “treating” open cracks.	FT