gemstone

Pearl

Calcium Carbonate (Aragonite/Calcite) with Conchiolin, CaCO3

Hardness: 2.5 to 4.5 on the Mohs scale. Color: White, cream, silver, gray, black, golden, or various pastel shades. Luster: Pearlescent (or orient, a shimmering iridescence). Crystal structure: Orthorhombic (as aragonite platelets). Cleavage: None. Specific gravity: 2.60 to 2.85.

Hardness: 2
Luster: Pearlescent (or orient, a shimmering iridescence)

Identified August 3, 2026More gemstone →

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Physical properties

Formation & geological history

Formed inside the soft tissue (mantle) of a living shelled mollusk (saltwater oysters or freshwater mussels). When an irritant enters the shell, the mollusk secretes layers of nacre (mother-of-pearl) around the foreign object.

Uses & applications

Primarily used in fine jewelry, such as necklaces, earrings, rings, and bracelets. Also used in traditional medicines and cosmetics in various cultures.

Geological facts

Unlike most gemstones that are mined from the earth, pearls are organic gems produced by living organisms. Natural pearls are extremely rare, which led to the development of cultured pearl farming.

Field identification & locations

Identified by its distinctive organic luster and texture, warm feel to the touch compared to glass beads, and a gritty texture when gently rubbed against the edge of a tooth due to the microscopic aragonite platelets.

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