silicates
Diopside
CaMgSi2O6
- Also known as
- chrome diopsideRussian emeraldstar diopside
- Crystal system
- monoclinic
- Hardness
- 5.5–6.5 on the Mohs scale
- Lustre
- vitreous
- Colour
- Green to near black, occasionally colourless
- Where it forms
- In metamorphosed limestones and in ultramafic rocks. Chrome diopside comes from kimberlite and is another diamond indicator mineral.
- Chiefly from
- Inagli, Siberia, RussiaMadagascarItalyPakistan
Why it is that colour
Iron gives most greens. Chromium gives the intense green of chrome diopside, which is the material sold as a gem.
Safety
Safe to handle. Chrome diopside is soft for a ring stone and abrades in wear.
Where it comes from
Chrome diopside comes almost entirely from one deposit in Yakutia in Siberia, and mining there is limited by climate to a few months a year. Supply is genuinely constrained by weather.
Historical use
A rock-forming mineral of considerable geological importance, and one of the indicator minerals used to find kimberlite pipes.
Recorded as history and attributed where possible. That a stone was used for something establishes that people used it, not that it worked.
What is attributed to it, and since when
Named in 1806 from the Greek for double appearance, after its optical properties. No traditional attribution; all meanings are modern.
Described, not endorsed. Dating a claim is not the same as assessing it — but an association that first appears in a book published in 1985 is not an ancient inheritance, whatever the label says. A sincere account of feeling better is compatible with the stone doing nothing — see the placebo effect.
Sold as this, but not
Worth knowing
Chrome diopside is another entry in the chromium sequence — the same element that reddens ruby and greens emerald, tsavorite and uvarovite, doing it again here. It is inexpensive, intensely coloured, and too soft to wear well, which is a combination that keeps it out of fine jewellery and in the tumbled-stone trade.
The Siberian supply constraint is unusual enough to note. The Inagli deposit is in Yakutia, one of the coldest inhabited regions on earth, and mining is seasonal because the ground is frozen for most of the year.
Identity checked against IMA-CNMNC master list, June 2025.