Appearance
Since demantoids are the green variant of andradite garnet, they are inherently always green, however the precise shade can vary from a harsh yellowish green to almost the exact shade of a fine emerald. Iron is the reason for the brownish hue in some stones. Because of its very high dispersion (0.057), “fire”—rainbow-colored flashes of light—is frequently visible. However, occasionally, the stone’s green body color might make this effect less evident.
Although lighter, yellowish green stones exhibit significantly more fire, stones with deeper green hue are usually highly prized. Therefore, the choice of stone color or fire might depend on personal taste; some people prefer the greener, more yellowish-green stones.
Geographical Distribution
Although demantoid garnet is currently mined in Canada, Namibia, Iran, Italy, Pakistan, and Madagascar, the Russian variety is still the standard for all other varieties.
History
While garnets have been known since antiquity, the demantoid form was not found in the western central Ural Mountains of Russia until 1868. The discovery was an alluvial deposit close to the village of Elizavetinskoye, approximately 110 km (70 mi) northwest of Ekaterinburg along the Bobrovka River. The extremely refractive aspect of the gem material, which is unusual for garnet, astounded the miners right away. Referred to as “demantoid” (from the old German word Demant, which means diamond), they started drawing comparisons between it and diamonds. Given its high dispersion and brilliance, the cause is evident.
A second discovery was made on the Chusovaya and Chrisolitka Rivers, southwest of the settlement of Poldnevaya, 75 kilometers (47 miles) south of Ekaterinburg. Additionally, deposits can be discovered in the demantoid placer subsurface up to 3 meters (10 feet) deep. This region contains five distinct demantoid deposits. Due to its uncommon green hue and larger dispersion than a diamond, this gemstone rose to prominence and became highly valued. Since the renowned Peter Carl Fabergé used them to create jewelry, demantoids were well-liked in Russia from the time of their discovery until roughly 1919. These jewels were out of vogue in austere Communist Russia.
The Bobrovka River yielded more stones throughout the 1970s and 1980s. In the central Ural Mountains, virtually little manufacturing took place about 1999.
Chemical Composition
Andradite is a garnet that is rich in iron and calcium. The demantoid green color is due to chromium substitution in the chemical formula, Ca3Fe2(SiO4)3. The yellow of the stone is caused by ferric iron.
Uses
The majority of the time, demantoids are used in jewelry, including bracelets, necklaces, rings, earrings, brooches, and more.
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