Dioptases usually occur as micro-crystals. Although larger crystals can be found, they rarely have large clean areas, so any faceted gems rarely weigh more than 1 or 2 carats. Perfect cleavage can also make these gems difficult to facet. However, lapidaries can cut sizable cabochons from translucent dioptase masses.
A hydrous copper silicate, dioptase has been called “emerald copper” because of its color. Dioptase can form in close association with malachite, another copper-bearing mineral. You may find dioptase specimens sometimes described as “emerald malachite,” perhaps because their crystalline formations appear “gemmy,” like emeralds, and their color is similar to that of more well-known malachites. Of course, dioptase, malachite, and emerald constitute three distinct gem species. This is likely another example of vendors falsely connecting a gemstone — in this case — with not one but two more well-known gemstones in an effort to increase consumer interest (and prices). See our list of false or misleading gemstone names for more examples.
Scientists have synthesized dioptases. However, there is no known jewelry use for this lab-created material.
Tsumeb, Guchab, and Kaokoveld, Namibia produce the world’s finest crystals, with superb color, on matrix, and up to 2 inches long. Some are transparent but also filled with cleavage planes and fractures.
The dioptase type locality, Altyn-Tyube, Kazakhstan, also produces fine crystals.
With perfect cleavage and a hardness of 5, dioptases need protective settings whether faceted, cabbed, or raw. These gems have greater susceptibility to scratches than other, more popular jewelry stones like tourmalines, peridots, and even emeralds. However, dioptases make excellent choices for earrings or brooches.
Due to its copper content, dioptase dust is toxic. Accidental ingestion could lead to acute distress, like vomiting, and chronic exposure could lead to liver and kidney damage. Faceters should wear protective masks and, ideally, use a glovebox to prevent inhaling or ingesting dioptase particles during cutting, polishing, and cleaning. However, wearing or handling finished pieces should pose no hazards.
Due to cleavage and possible fractures, dioptases should only be cleaned with a soft brush, mild detergent, and warm water. Consult our gemstone jewelry cleaning guide for more care recommendations.