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: np =1,663 – 1,669, nm =1,671 – 1,705, ng =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