gemstone

Faceted black gemstone, likely black spinel

Spinel, MgAl₂O₄ (identification from appearance is uncertain)

AI-generated identification · may be incorrect

Opaque to near-opaque, black, with strong vitreous luster and a square step-cut. Spinel has Mohs hardness 8, cubic crystal structure, and no cleavage; other black gems can look similar.

Identified October 11, 2026More gemstone →

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Physical properties

Opaque to near-opaque, black, with strong vitreous luster and a square step-cut. Spinel has Mohs hardness 8, cubic crystal structure, and no cleavage; other black gems can look similar.

Formation & geological history

Natural spinel crystallizes in metamorphic rocks and some igneous deposits, often in marble or as water-worn placer grains. Its age depends on the deposit; the image alone cannot establish whether this stone is natural or synthetic.

Uses & applications

Used in jewelry and collected as a faceted gemstone; black spinel may also be used as an affordable diamond alternative.

Geological facts

Black spinel is distinct from black diamond and typically has a more glassy luster. Gem testing or a jeweler’s refractive-index measurement is needed for a confident identification.

Field identification & locations

The dark color and faceting are consistent with black spinel, but black sapphire, garnet, or synthetic material are alternatives. Common sources include Thailand, Sri Lanka, and Myanmar.