Gem/Gem Topic of the Month

Each month this section will feature either a topic of interest to gem lovers or one special gemstone with background on the material and its value.

Go to: Homepage -- what's new in faceted gems -- what's new in designer cabochons and gem carvings -- gem of the month -- gem of the month archive -- birthstone of the month -- key to all the codes used on the ACS site -- definitions of terms used on the ACS site -- how to order -- about ACS -- about the ACS cutters -- settings for these gems --faceting information -- purchase UltraTec equipment

 

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July, 1998 (Revised, August, 2004)

Chrome Diopside

I was originally prompted to write these comments on chrome diopside after seeing a television shopping network's promotion of this gem as "Russian diopside" and their featuring it extensively in rings. Chrome diopside is a deep, spectral green variety of the mineral diopside which derives its color from chromium. A Russian find in 1988 is the source of the Tsavorite-like stones that are gaining in popularity and recognition today.

As beautiful as the material is, its use in rings is risky at best. A hardness of (5.5-6), moderate brittleness, and cleavability limit its use to pendants, brooches and earrings unless placed in highly protective settings and given gentle treatment. For these other uses, though, the stone is beautiful and under-appreciated. Good cutting is important as this variety, especially in larger sizes, can be very dark. A good cut with fairly shallow angles can improve brilliance. Cabochons can be distinctive and attractive, and collectors eagerly look for the rare cat'seye form.

A well cut piece of chrome diopside is a beautiful sight to behold, and a reasonably priced alternative to Tsavorite or chrome tourmaline.


Value

The prime value factor for this gem is color, with medium dark green stones at the top. Such a stone in a larger size (2 cts or more) is especially rare since so many larger pieces suffer from light extinction and are too dark. Cat'seye stones bring a premium price. Fine cutting enhances value considerably by adding scintillation and brilliance.


Gemological Data

Makeup: a calcium, magnesium silicate

Luster: Vitreous

Hardness: 5.5-6

Crystal structure: Monoclinic

Fracture: conchoidal to uneven

Cleavage: perfect in two directions

Density: 3.29

RI: 1.66 - 1.72

Birefringence: .029

 

All text and images, unless otherwise designated, © 2004 Barbara Smigel

 


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Go to: Homepage -- what's new in faceted gems -- what's new in designer cabochons and gem carvings -- gem of the month -- gem of the month archive -- birthstone of the month -- key to all the codes used on the ACS site -- definitions of terms used on the ACS site -- how to order -- about ACS -- about the ACS cutters -- settings for these gems --faceting information -- purchase UltraTec equipment