“Chrome Diopside: a beautiful gem with an ugly name.”
Gem by Gem, International Colored Gemstone Association
Named in 1800, Diopside draws its name from the Greek ‘Di’ (two, or double) and ‘opsis’ (aspect or view), referring to its double refraction or pleochromism. Another commercial name is ‘Chrome Diopside’, but the preferred term for stones sourced from Russia is ‘Russian Diopside’.
Other names include ‘Imperial Diopside’, ‘Vertelite’ and ‘Serbelite’. It has also been called ‘Siberian Emerald’, although this is not only incorrect, but also deceptive; Russian Diopside is neither an Emerald, nor is it a member of the Beryl family.
Chemical composition of Diopside
Diopside belongs to the mineral group of Silicates, represented by the chemical formula CaMG(SiO3)2. Although it may be found in very large crystals (up to 50 cm), only a tiny percentage is suitable for processing into a precious stone.
On Moh’s hardness scale, Diopside scores between 5.5 and 6.5, striations are white, it fractures roughly and conically, and presents perfect cleavage in two directions.
Raw Chrome Diopside crystals
Described for the first time in 1800 by mineralogist José Bonifácio de Andrada e Silva, Diopside is extracted in Brazil, Myanmar, Canada, China, Finland, India, Italy, Kenya, Madagascar, Pakistan, Russia, Western Africa, Sri Lanka and the United States.
Diopside is an allochromatic gemstone, meaning other colored; its wonderful greens are caused by the presence of chrome or iron. For example, the yellow-green varieties of African Diopside, which bear similarities to Peridot, are due to iron. Diopside exists in a broad range of colors: blue, brown, gray, purple, white and transparent.
The history of Diopside
Diopside was also known as ‘the gem that weeps’ due to its supposed ability to alleviate trauma through purifying tears. Already used as a precious gemstone for jewelry by the ancients, Diopside, particularly in its star-shaped form, gave rise to a variety of beliefs. The ancient Greeks, for example, believed that Star Diopside was a small shining star, becoming stone after having fallen to earth. The sheen of the gemstone was believed to contain starlight.
Properties of Diopside
The clarity standard for Russian Diopside is eye-clean (no visible inclusions visible to the naked eye from a distance of 15 cm). Therefore, only a minimal proportion of the extracted material is suitable for use in jewelry. Russian Diopsides are usually quite small (less than one carat); examples larger than five carats are not available.
Russian Diopside is bichromate (two colored, yellow and green); this dichromatism should not create difficulties if the gemstone is cut skillfully.
Usually, Russian Diopside is faceted using a brilliant or stepped cut, in a variety of shapes. Round and oval shapes are the most common; other shapes are generally more expensive.
Varieties of Diopside
Tashmarin® is the commercial name for the light green Chrome Diopside mined in the Tien Shan mountain range (called the “celestial mountains”) in the Xingjiang Uyghur Autonomous Region of Western China, registered by the Columbia Gem House in 2001. Due to lesser concentrations of chrome, its color is less intense than that of Russian Diopside.
Violan is a rare variety of Diopside with a purple-blue color found in Saint-Marcel, Val d’Aoste. Its color is due to the presence of high concentrations of manganese.
Star Diopside with four rays is found in India, and is also known as Black Star Diopside due to its black or blackish-green color. Star Diopside has two straight rays, while the other two are angled relative to the others. The star effect is only visible in a cabochon cut, or in a convex shape that has been polished accurately but not faceted. A good cut is capable of displaying a neat star with straight and equidistant rays.
Russian Diopside displays beautiful, rich and pure greens, sometimes with a slight bluish hue. As is the case with Emeralds, the blue can slightly accentuate the depth, richness and warmth of the intense greens. This rare and fascinating variety of Diopside has chrome to thank for its typical green hues. In 1988, Russian Diopside conquered the market in a heartbeat, once European gemstone merchants discovered this new Russian stone with a color similar to Emerald and Tsavorite, but that was far more accessible. Following liberalization of the former Soviet Union’s market, Russian Diopside is now exported in the same quantities as Alexandrite, Diamond and Emerald.
In addition to its objective beauty, its origins are particularly interesting. It is extracted in Yakutia (Sakha), a remote federal Russian republic located in Western Siberia. Located in the extreme north of Asia, Yakutia is noted for its harsh climate; the Verkhoyansk mountains are the coldest place in the entire Northern hemisphere. In January 1926, temperatures dropped below -71.2°C in Oymaykon.
A Yakutian hunter in 1979 in Yaktuia, home of Russian Diopside.
Yakutia is also the source of 99% of all Russian Diamonds, which represents 23% of global Diamond production. These two gemstones also share another fascinating connection: Diopside is an important element in the Earth’s crust, as it is located in diamondiferous tracts, and is therefore a useful indicator of the presence of Diamonds, and Diopside is even occasionally found as in inclusion in Diamonds themselves.