Chemical composition -- Calcium magnesium silicate.
Color -- Many colors, but the best known is deep green (chrome diopside), which derives its color from chromium impurities.
Optics -- R.I. 1.67-1.70.
Durability -- Hardness 5.5-6.5. Although recently promoted by some in the jewelry industry, diopside is too soft to wear well in rings and should be used only in earrings, pins, and pendants.
Crystal structure -- Monoclinic .
Specific Gravity -- 3.22-3.38.
Sources -- The best known sources for chrome diopside are Russia and Kenya. Faceted stones are usually under 5 carats, and the extremely dark color makes larger stones appear black. Star and cat's-eye diopside is abundant from India.