Emerald is a variety of the mineral beryl, colored green by trace amounts of chromium varying of a blue hue of color. The Russian name "emerald" is derived from the Turkish name of this stone "zümrüt", distorted during the times from the Semitic root "shine" (for example, the closest in sounding in Hebrew "בָּרֶקֶת" - "bareket" and in Sanskrit "मरकत" "Marakata" is an "emerald").

Chemistry: Ве3А12[Si6O18];

Crystal system: Hexagonal, dihexagonal-dipyramidal crystal class (point symmetry group);

Color: Green, bluish green.

The Al63+ isomorphic substitution for Cr63+. is cause of green color. Additional shades are caused by the occurrence as an isomorphous impurity of the V63+ and Fe43+ ions (in the ionically bound [O2- – Fe43+]), as well as Fe62+ and Fe42+ ions. Sometimes the influence of the Fe63+, Mn63+, Ti63+, as well as Mg62+, Ca62+ ions of other metals affect the color of the emerald.

Identification properties

Physical properties
Mohs hardness: 7.5-8
Density: 2.6 – 2.9 g/cm3
Cleavage: imperfect
Fracture: conchoidal
Optical properties
Optical character:

anisotropic, uniaxial *, negative

* Sometimes anomalously biaxial (refers to twins, and distorted crystals)

Refractive Index: no = 1.567-1.604, nе = 1.561-1.596
Birefringence: 0.005 – 0.009
Pleochroism: Green shades to colorless
Dispertion: 0.014 (BG)
Luster: vitreous

Inclusions and structural inhomogeneities

Two- and three-phase inclusions