South Sea Pearl
Pearls form in a variety of mollusks in seawater and freshwater. A mollusk forms a pearl in response to a stimulus, as part of its defense against an intrusion. The shell-forming tissue coats an irritant that stimulates the growth of aragonite or calcite, commonly known as nacre, thus creating the pearl. When this occurs naturally, it is called a natural pearl; if man implants a nucleus within the mollusk's body, the resulting pearl is called a cultured pearl. Similar to other gems, pearls are evaluated by several factors: size, shape, color, luster, surface quality, and nacre quality.
Some of the most densely populated pearl oyster beds in the world lie off the coast of northern and western Australia. This remote location with often rough seas is the source of some of the largest and finest pearls in the world, known as South Sea pearls. Pinctada maxima, the mollusk that produces these white to golden-yellow pearls, is noted for its thick white shell and sometimes reaches more than 12" in diameter. This collection of 37 exquisite natural and cultured South Sea pearls shows the range in color and shape from these famed pearl beds.