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Photograph of the uncut Impreial topaz (116879) and a faceted topaz (G3401) from the national gem and mineral collection
Photo by Chip Clark
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About this object
Until the 1950s, topaz was known almost exclusively as a yellow to golden gemstone. But since then, the routine radiation and heat treatment of pale-colored topaz to turn it shades of blue has changed the public’s perception of this gem. To most of the present generation of jewelry buyers, topaz is recognized primarily as an affordable blue gemstone. The highly prized “imperial topaz” is an intense golden to reddish-orange color and is found primarily at Ouro Preto, Brazil. The imperial topaz crystal and gem pictured here weigh 875.4 and 93.6 carats respectively. More commonly, topaz is colorless to pale blue or yellow. Pink or red stones are rare, although pink stones can be produced by heating the golden brown topaz from Ouro Preto. Topaz is renowned for its ability to grow huge gem-quality crystals. The National Gem and Mineral Collection has two very large topaz crystals that weigh 153lb and 111lb, both from Minas Gerais, Brazil, as well as a 22,892.5-carat (10.1 lb) faceted topaz, that is the largest gem in the Collection. The reason that such large gem-quality crystals can be found in museums is that at the time they were discovered, their pale color made them unattractive for cutting into gems. This would not be the case today, as these large gemmy pale crystals are the essential raw material for the modern blue topaz market. The National Gem Collection has a beautiful display of topaz gems and crystals on exhibit at the National Museum of Natural History.
denotes specimens currently on exhibit
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