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Chrome-diopside

Chrome-diopside is a chromiferous variety of the diopside mineral. The name of the variety comes from the name of the mineral species - “diopside” and the chromophore impurity of the chemical element, the ions of which cause the characteristic green color - “chrome”.
Chrome-diopside is colored with a basic green color with an admixture of shades of yellow or blue, depending on additional chromophore impurities. Coloring, as a rule, has a high degree of saturation. The chromophore content of chromium on average is about 0.5%, but in some cases it can reach up to 2% (in terms of Cr2O3).
In the 1990s, chrome-diopside was advertised under the trade name "Yakut emerald", but since this term can be misleading with respect to the mineral species, this brand was found to be incorrect and not recommended for use. However, you can still hear this beautiful and romantic name - "Yakut emerald", which has no relation to either emerald or beryl.

Chemistry: Ca(Mg,Cr)[Si₂O₆];

Crystal system: Monoclinic, Monoclinic-prismatic symmetry class (point symmetry group);

Color: The main green color of chrome-diopside is caused by the presence of an impurity of Сr₆³⁺ ions, isomorphically replacing magnesium in the structure of diopside, and the yellow and brown shades are associated with an isomorphic admixture of iron ions Fe³⁺. In some species, isomorphic V³⁺ impurity also influences coloring.

Identification properties

Physical properties
Mohs hardness:	5.5 – 6.5
Density:	3,22 – 3,40 g/cm³
Cleavage:	on {110} average
Fracture:	rough, staggered

Optical properties
Optical character:	anisotropic, biaxial (positive)
Refractive Index:	n_p =1,663 – 1,669, n_m =1,671 – 1,705, n_g =1,693 – 1,728
Birefringence:	0.025 – 0.031
Pleochroism:	weak (yellowish green - green)
Dispertion:	0,017 – 0,020 (BG)
Luster:	glassy

Inclusions and structural inhomogeneities

Gem basic treatments

Treatment	Goal
Impregnated with adhesive	Strengthen, prevent splintering, improve cleanliness
Impregnation with various coloring compounds	Altering the gem visual color
Surface coating by applying a various coloring agent	Altering the gem visual color

Synthetic or Imitation gem materials

Synthetic chrome-diopside is not produced for the jewelry industry.

As imitations of chrome-diopside are used as follows:

synthetic minerals with similar color (cubic zirconia, garnets, spinel, corundum);
doublets and triplets: glass + natural or synthetic chrome diopside / diopside;
color glass;