Diopside
Diopside is not really a name to attract the jewelry-buying public and it doesn't invoke the reality of this vibrant gem, with its dramatic chrome green colour. That is why efforts are being made to come up with a more tempting designation.
Diopside comes in a number of saturated colours: bottle green, brownish green, light green, brown and purple. The gem is highly refractive, so faceted transparent stones appear lively and brilliant with a vitreous lustre. Sometimes diopside can be virtually black, with fibres that lie parallel to each other and produce a distinctive four-rayed star. There is also an opaque purple to violet-blue variety called violane, which occurs in Italy and the United States.
CHROME DIOPSIDE
This is the most important and valuable variety of diopside, with a vivid emerald-green colour due to the presence of chromium. Russia is the major commercial producer of high-grade chrome diopside; the Siberian mines process between 10,000 and 15,000 carats of faceted gem material per month. The bulk of this is in calibrated sizes up to 9x7-mm ovals (2 carats in weight). Larger single gemstones are also cut, but in much smaller quantities. It is rare to find "clean" chrome diopside of over 7 carats. Some chrome diopside is now marketed under the name VerteliteTM.
Treatments and imitations
As yet, diopside is not enhanced. It is not treated for colour and, unlike emeralds, there is no evidence of oiling or fracture-filling with resin.
Pricing diopside
The price of "clean" bright chrome diopside is moderate if you stay under 2 carats, but large stones are more expensive due to rarity. Good-quality bead material is available, but an entire row of chrome diopside beads will cost!
Working with diopside
- Diopside is sensitive to heat, so avoid soldering and polishing with the stone in situ and don't use steam cleaners or ultrasonics. Avoid any contact with bleach or cleaning liquids as acids will dull the polish of the gemstone.
- Diopside has a rough, uneven fracture and perfect cleavage in two directions at nearly right angles. Gem-quality diopside often contains flaws resulting from internal stresses and the inherent fragility of the material, which is why it is so difficult to find large, "clean" rough material. A rectangular step cut is typically used because the crystal shape is columnar, and faceted stones are usually cut slightly shallow to obtain the best colour, as the colour saturation of diopside can make a stone appear dark. However, the perfect cleavage means that diopside is vulnerable to impact or undue pressure, so an oval or round brilliant cut is much safer than a shallow rectangular cut. The prices of the "safer" cuts will be much higher, to compensate for the far greater waste (weight loss) of rough material created by an oval or round.
- Diopside is perfectly safe for jewelry as long as it is for occasional use. Faceted diopside is not ideal for a ring stone; a cabochon in a rub- over setting would be much more robust.
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