Tahitian Pearl
Biogenic Calcium Carbonate (Aragonite/Calcite), CaCO3
Rock Type: mineral

Physical Properties
Hardness: 2.5–4.5; Color: Black, gray, silver with blue/green overtones; Luster: Pearly/nacreous; Crystal structure: Orthorhombic (aragonite platelets); Specific Gravity: 2.60–2.85.
Formation & Geological History
Formed biologically within the 'Pinctada margaritifera' (black-lipped oyster). It is created as the mollusk deposits layers of nacre around an irritant or implanted bead.
Uses & Applications
Primarily used in high-end jewelry (earrings, necklaces, rings) and as highly prized collector items due to their unique dark colors.
Geological Facts
Unlike white pearls, Tahitian pearls are naturally dark because of the black lip of the oyster they come from. They are often called 'Black Pearls' but exhibit a vast rainbow of iridescent overtones.
Field Identification & Locations
Identify by their organic luster and 'cool' touch. In the field, look for the 'tooth test' (a gritty feeling when rubbed against teeth) to distinguish genuine nacre from smooth plastic/glass imitations. Found mostly in French Polynesia.
Identified on: 4/27/2026
Mode: Standard