Pearl (nacre)

Physical Properties

Hardness: 2.5–4.5; Color: White, cream, or silver; Luster: Pearly (iridescent); Crystal structure: Orthorhombic (microcrystalline); Specific Gravity: 2.60–2.85

Formation & Geological History

Formed within the soft tissue (mantle) of living shelled mollusks; concentric layers of nacre are deposited around an irritant.

Uses & Applications

Primarily used in jewelry, fashion accessories, and as a collector's gemstone; historically used in cosmetics and traditional medicines.

Geological Facts

Pearls are the only gemstones created by living creatures. Unlike mineral stones, they require no cutting or polishing to reveal their natural beauty.

Field Identification & Locations

Identify by the 'tooth test' (rub gently against teeth to feel a gritty texture) or by observing orient and overtones; commonly found in both saltwater (oysters) and freshwater (mussels).

Identified on: 4/25/2026

Mode: Standard