Pearl

Physical Properties

Hardness: 2.5–4.5; Color: White, cream, pink, silver; Luster: Pearly (iridescent); Crystal structure: Orthorhombic (specifically as aragonite tablets); Cleavage: None; Specific gravity: 2.60–2.85

Formation & Geological History

Formed biogenically within the soft tissue (mantle) of living shelled mollusks (oysters/mussels) as a defense mechanism against irritants. Modern pearls are often 'cultured' by intentional seeding.

Uses & Applications

Primary use in fine jewelry (necklaces, earrings, rings) and ornamentation. Historically ground for cosmetics and traditional medicine.

Geological Facts

Pearls are the only gemstones in the world to be created by a living creature. Unlike other gems, they require no cutting or polishing to reveal their natural beauty.

Field Identification & Locations

Identify by the 'tooth test' (rubbing across teeth reveals a gritty texture for real pearls) and looking for the characteristic 'orient' or rainbow-like surface shimmer. Found in marine and freshwater environments globally.

Identified on: 4/25/2026

Mode: Standard