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Smithsonian National Museum of Natural History


Composite image showing change from green to purple in a color-change garnet (NMNH G11432)
Photo by Ken Larsen. Click to zoom.
Catalog Number NMNH G11432-00
Locality Sri Lanka
Weight 4.21 ct

Gift of Richard and Rita Ashley in 2012.

Although garnets are commonly thought of as deep red stones, the name garnet actually refers to a family of 15 distinct minerals. All members of the garnet family share the same basic atomic structure and are closely related, but they differ in chemical composition. Five garnet minerals are commonly used as gemstones, and they can exhibit the complete spectrum of colors. They are pyrope, almandine, spessartine, grossular (varieties hessonite and tsavorite), and andradite (variety demantoid). The garnets make up two solid solution series: pyrope-almandine-spessartine and uvarovite-grossular-andradite. This color change garnet is a pyrope-spessartine. Color change garnets are rare and interesting collectors’ stones and have been found in Madagascar, Tanzania, Kenya, and Sri Lanka. This garnet displays a pronounced color change from pinkish-purple under incandescent light to a brownish-green under fluorescent or sun light, due to impurities of chromium and vanadium. Color change garnets can be mistaken for alexandrite, and their value is dependent on the color, clarity, and degree of color change.This 4.21ct color change garnet is a modified step cut and is from Sri Lanka.



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