mineraloid
Black Pearl (Tahitian or Irradiated Type)
Organic gemstone (Calcium Carbonate with Conchiolin Binding)
Hardness: 2.5–4.5 (Mohs scale); Color: Black with peacock, green, or purple overtones; Luster: Pearly to metallic; Structure: Amorphous/concentric; Specific Gravity: 2.60–2.85.
- Hardness
- 2
- Color
- Black with peacock, green, or purple overtones
- Luster
- Pearly to metallic
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Physical properties
Hardness: 2.5–4.5 (Mohs scale); Color: Black with peacock, green, or purple overtones; Luster: Pearly to metallic; Structure: Amorphous/concentric; Specific Gravity: 2.60–2.85.
Formation & geological history
Formed inside the soft tissue (mantle) of a living shelled mollusk, specifically the Pinctada margaritifera. They can be found in various eras, but modern specimens are typically harvested from cultured sources in French Polynesia.
Uses & applications
Primarily used in high-end jewelry (necklaces, earrings, rings) and as loose collectibles for gemstone enthusiasts.
Geological facts
Black pearls were historically very rare and associated with royalty; today, most are 'cultured' by human intervention. True Tahitian black pearls naturally produce their dark pigment, unlike white pearls that are dyed or irradiated to appear black.
Field identification & locations
Identify by looking for a 'pearly' luster and checking for minor surface imperfections (real pearls are rarely perfectly smooth). In the field, they are only found in marine mollusks. For collectors, use the 'tooth test'—real nacre feels gritty against the teeth.
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