mineral

Black Pearl (Tahitian-style Cultured Pearl)

Calcium Carbonate (Aragonite) with Conchiolin (CaCO3)

Hardness: 2.5–4.5 on Mohs scale. Color: Dark grey, peacock green, or iridescent purple/black. Luster: Pearly to iridescent. Crystal structure: Orthorhombic (microcrystalline). Specific gravity: 2.60–2.85.

Hardness: 2
Color: Dark grey, peacock green, or iridescent purple/black
Luster: Pearly to iridescent

Identified March 22, 2026More mineral →

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Physical properties

Formation & geological history

Biogenic formation within the mantle tissue of mollusks, specifically the Pinctada margaritifera (black-lipped oyster). Layers of nacre are deposited over a nucleus over 18–24 months in warm saltwater environments.

Uses & applications

Primarily used in high-end jewelry (necklaces, rings, earrings) and as a collector's gemstone. Historically significant as a symbol of wealth in many cultures.

Geological facts

Unlike 'black' pearls that are dyed, authentic Tahitian pearls get their color naturally from the organic pigments in the Pinctada oyster's shell. They are often called 'The Queen of Pearls'.

Field identification & locations

Identify by 'the tooth test' (feeling for a gritty texture against the teeth), looking for natural surface pits, and checking for 'orient' or overtones. Distinct from common freshwater pearls by their deep, dark body color and large size.

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