gemstone

Pearls

Pearl: biomineralized aragonite (CaCO₃) and conchiolin

AI-generated identification · may be incorrect

Hardness about 2.5–4.5 Mohs; white to cream, rounded, nacreous pearly luster, and layered concentric structure. These appear to be drilled cultured pearls, likely freshwater or saltwater, rather than solid mineral crystals.

Identified August 11, 2026More gemstone →

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Physical properties

Formation & geological history

Pearls form inside mollusks when nacre is deposited around an irritant or implanted nucleus; cultured examples are human-initiated but naturally nacre-coated. Individual pearls commonly form over roughly 6 months–3 years, with no conventional geological age.

Uses & applications

Used primarily in jewelry and ornamentation; they have little industrial or construction use. Value depends on luster, surface cleanliness, roundness, size, nacre thickness, color, and whether they are freshwater or saltwater.

Geological facts

Nacre consists mainly of microscopic aragonite platelets arranged in a brick-like structure, producing iridescence. Pearl is an organic gemstone, not a rock in the strict petrological classification.

Field identification & locations

Identify by cool, slightly gritty feel, strong nacreous luster, surface growth marks, and a flame-like or layered appearance around drill holes; imitation glass or plastic often looks too uniform. Common sources include China, Japan, Australia, Indonesia, and the Persian Gulf region.