Image taken from Beautiful Pearls . The most popular colors are white, pinks, and creams, but pearl may also be silver, golden, blue, green, and black. The color varies with the type of mollusk, the water, and the color of the upper conchiolin layer. Treated pearls are colored peach, lavender, and other colors, while some are bleached to be even whiter. Even though the hardness is only 2.5-4.5, they are compact and difficult to crush.
Pearls vary in size from a pin head to pigeon's egg size.
Cultured Pearl Ring. Image taken from Amazing Pearls . Cultured Pearl Earrings image taken from Amazing Pearls . Genuine river pearls are not common because pollution has virtually eliminated the oyster habitats. Cultured seawater pearls go back to China, 13th century, and rounded freshwater pearls were first produced by Carl von Linnaeus about 1721.