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Corundum (var. ruby)

Corundum (var. ruby) (NMNH G11436-00) from the National Gem Collection.
Photo by Ken Larsen. Click to zoom.
Catalog Number NMNH G11436-00
Locality Afghanistan
Weight 4.02 ct

Purchased with funds from the Tiffany & Co. Foundation in 2012.

Ruby is the red variety of the mineral corundum. Pure corundum is colorless, but small amounts of impurity atoms can impart a range of colors. In this case, chromium is responsible for the beautiful red color of the ruby. Any other color of corundum is called sapphire, which can occur in many colors, including blue, purple, green, yellow, pink and orange. The most important source of fine rubies has been Burma, and in fact the term “Burmese Ruby” is synonymous with the best and most valuable rubies. These rubies have an intense red to slightly pinkish-red color and are medium-dark in tone, commonly referred to as “pigeon’s blood.” Rubies can be found in many localities, including Sri Lanka, Thailand, Cambodia, Vietnam, India, Madagascar, Malawi, Mozambique, Tanzania, Australia, Afghanistan, Tajikistan, Pakistan and the U.S. This corundum gem has a medium purplish-red color and is the first ruby from Afghanistan in the National Gem Collection, acquired in 2012 with funds from the Tiffany & Co. Foundation endowment.

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