A pearl is generally composed of calcium carbonate and mainly aragonite. The crustacean mollusk family forms the pearl when a foreign particle enters the mantle of the mollusk and forms concentric layers of pearls around the cells. Pearls can vary in shape. The most valuable pearls are spherical or drop-shaped, with a deep luster, natural and good color.
Species: pearl-bearing oyster family - Margaritiferidae ♦ Chemistry: caclium carbonate and conchiolin ♦ Color: white, blue, green, yellow, orange, brown, pink, purple, gray, black, multicolored ♦ Cleavage: none ♦ Fracture: uneven ♦ Transparency: opaque ♦ Luster: pearly ♦ Crystal System: orthorhombic ♦ Moh's Hardness: 2.5-4.5 ♦ Localities: worldwide, natural pearls found in Australian Indian Ocean