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Demantoid


In 1868, during the reign of Tsar Alexander II of Russia - after whom the mineral alexandrite was named - a new garnet variety was discovered in the Ural mountains. This andradite garnet which is usually bright yellowish-green is one of the highest priced gemstones one can find, especially when it has the rare and intense grass green color which rivals emerald. It has a very high brilliancy and has a high dispersion, which adds to the beauty of the hue. It has a relative high refractive index, reasonable hardness and a vitreous to adamantine luster.

The major deposits for demantoid are found in alluvial deposits in The Ural mountain range along the Bobravka River and more recently demantoid was discovered in Namibia. The superb color of the finest Russian material is the hue by which all demantoids are judged. Stones with typical and well formed horsetail inclusions are some of the most coveted gemstones. The famous jeweler Fabergé used demantoids in his jewelry and made it a popular gemstone. At the end of the 19th century there was a true 'demantoid fever'.

The name of this gem means "diamond like", most probably due to its dispersive powers which actually outrank diamond but are usually suppressed by its body color.


Gemological information for demantoid
ColorBrownish and yellowish-green to grass green and black
Crystal StructureCubic
Refractive Indexca. 1.89
DurabilityVery durable
Hardness6.5-7
FamilyGarnet - Andradite Species
Similar stonesDemantoid may be confused with Tsavorite Garnet, Peridot, Emerald, Diopside and Tourmaline
TreatmentsDemantoids can be heated to improve their color
Localities
Demantoid care
Ultrasonic cleaningNot safe
Steam cleaningNot safe
Warm soapy waterSafe
Chemical attactNot safe
Light sensitivityNone
Heat sensitivityNot safe
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