Chrome Diopside

Gem-quality chrome diopside is mined mainly in the mountains of eastern Siberia, Russia, near diamond-bearing kimberlite pipes; the Inagli deposit lies in the Sakha Republic (Yakutia). The short summer mining season limits supply. Deposits also exist in Pakistan, Afghanistan, Italy, Finland (Outokumpu), Austria, Tanzania, Kenya, Madagascar, Myanmar and India.

Chrome diopside shows weak yellow-green pleochroism, relatively high birefringence (about 0.028) and a chromium absorption spectrum with sharp lines near 490, 505 and 508 nm and a doublet near 690 nm. Its color resembles emerald, tsavorite garnet and chrome tourmaline; the trade names "Russian emerald" and "Yakut emerald" are misleading, as it is not emerald or beryl. Imitations include green glass, synthetic stones of similar color (cubic zirconia, garnet, spinel, corundum) and doublets or triplets. Synthetic chrome diopside is not produced for jewelry; Russian material is generally untreated, though the Moscow Gemological Center lists adhesive impregnation and coloring as possible treatments.

Diopside is relatively soft (Mohs 5.5–6.5) with one direction of perfect cleavage, and the International Gem Society rates its wearability as poor; protect it from knocks and scratches.

Chrome diopside from Russia began appearing in the jewelry industry in 1988 and became available in commercial quantities from the former USSR. In the 1990s it was advertised as "Yakut emerald", a name later judged incorrect. Since about 2013 jewelry brands in China have promoted it, first as an emerald alternative and increasingly as a gem in its own right.