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Smithsonian National Museum of Natural History

Cordierite (var. iolite)

No description of this
                                          asset is available
Photo by Ken Larsen. Click to zoom.
Catalog Number NMNH G10393-00
Locality India
Weight 10.32 ct

Gift of Mr. Dudley Blauwet in 2005.

Iolite is the gem variety of the mineral cordierite. The name “iolite” comes from the Greek word for “violet.” It has also been called “water-sapphire” as it resembles sapphire in color, but it is typically not as saturated in hue and tends to have color zoning. The color of iolite is commonly referred to as “inky,” a dark bluish-purple color, but also varies in color from blue to yellowish gray or brown. The gem is strongly pleochroic, appearing blue, bluish-gray, or grayish-yellow to colorless depending upon the direction from which the stone or crystal is viewed. Most gem cordierite is found in alluvial gravels as water-worn pebbles. It is commonly seen in jewelry today because it often times resembles the color of a tanzanite or a sapphire, but it is much more affordable. This 10.32-carat iolite is the first cordierite gem in the National Gem Collection from India.


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