gemstone
Faceted black gemstone, likely black spinel
Spinel (MgAl₂O₄); identification from the image is uncertain
AI-generated identification · may be incorrectAppears opaque to nearly opaque and black with a vitreous luster and faceted cut. Spinel has Mohs hardness 8, a cubic crystal structure, no cleavage, and specific gravity about 3.6; other black gems can look similar.
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Physical properties
Appears opaque to nearly opaque and black with a vitreous luster and faceted cut. Spinel has Mohs hardness 8, a cubic crystal structure, no cleavage, and specific gravity about 3.6; other black gems can look similar.
Formation & geological history
Natural spinel crystallizes in igneous and metamorphic rocks and can accumulate in alluvial deposits; deposits span many geological ages. The pictured stone has been cut and polished.
Uses & applications
Used in jewelry and as a collector gemstone; black spinel is also used as an abrasive in some industrial applications.
Geological facts
Black spinel is distinct from black diamond and is often confused with other dark stones, including garnet and synthetic materials.
Field identification & locations
Common sources include Sri Lanka, Myanmar, Thailand, and Madagascar. Confirm identity with gemological tests—appearance alone cannot distinguish spinel reliably.
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