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Smithsonian National Museum of Natural History

Andradite (var. demantoid)

Andradite (var. demantoid) (NMNH G11402-00)
Photo by Harold and Erica Van Pelt. Click to zoom.
Catalog Number NMNH G11402-00
Locality Russia
Weight 11.24 ct

Gift of Smithsonian Gem and Mineral Collectors in 2011.

The rarest and most valuable garnet gem is the green to yellowish-green variety of the mineral andradite, called demantoid. Demantoid was first discovered in Russia’s Ural Mountains in 1851, and from that time through the early 1900s they were popular in Russia and used in the finest jewelers’ workshops, often seen in Carl Fabergé’s jewelry and precious objects made for the Czars. Tiffany & Co. also made extensive use of demantoid gems in its jewelry during this period, as George F. Kunz, the chief gemologist for the company, was fascinated by the gem and purchased all the rough he could find. Demantoid means “diamond like,” and the gem displays an adamantine luster with amazing brilliance and dispersion. Gems larger than a few carats are extremely rare. Demantoid gems are usually high in clarity but may contain characteristic inclusions of byssolite, needle-like radiating inclusions referred to as “horsetails.” Today, because of limited supplies, demantoid maintains its status as a rare and valuable gem. Demantoid has been found in Italy and Iran, and more recently Namibia (1996). However, the Russian material continues to be the standard by which the gem is judged. This beautiful cushion-cut demantoid, found in Russia in the late 1990s, exhibits the vivid intense emerald-green color that is very rare and highly prized. At 11.24 carats it is a major upgrade for the National Gem Collection. It is a world-class gemstone and one of the largest and finest faceted demantoids known.


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