gemstone

Pearl

Calcium carbonate (Aragonite/Calcite) - CaCO3

Hardness: 2.5–4.5 on the Mohs scale. Color: White, cream, pink, silver, or iridescent pearlescent overtone. Luster: Pearly (orient). Crystal Structure: Orthorhombic (aragonite microcrystals bound by conchiolin). Cleavage: None. Specific Gravity: 2.60–2.85.

Hardness: 2
Luster: Pearly (orient)

Identified July 26, 2026More gemstone →

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Physical properties

Formation & geological history

Organic biomineral formed inside the soft tissue of a living shelled mollusk (bivalves or gastropods). It is produced as a defense mechanism against microscopic irritants by depositing concentric layers of nacre (mother-of-pearl).

Uses & applications

Extensively used as an organic gemstone in fine jewelry such as necklaces, rings, earrings, and bracelets, as well as decorative inlay work.

Geological facts

Pearls are one of the few organic gemstones in the world, alongside amber and coral. Cultured pearls are grown by inserting a nucleus into a mollusk, while natural pearls form spontaneously in the wild and are exceptionally rare.

Field identification & locations

Identified by its characteristic pearly luster, smooth round or baroque shape, and cool feel. The classic 'tooth test' (rubbing lightly against front teeth) reveals a slightly gritty texture for real nacre compared to smooth imitation glass or plastic beads. Found in marine environments (South Sea, Akoya, Tahitian) and freshwater rivers/lakes.

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