Characteristics of Pearl:

Chemical Name: Calcium carbonate

Formula: CaCO3

Colors: White, pink, silver, cream, brown, green, blue, black, yellow

Structure: Amorphous

Hardness: 2.5-4.5

Specific Gravity: 2.60-2.85

Refractive Index: 1.52-1.59

Lustre: Pearly

Locations: Costal waters of Japan, China, Australia

What is Pearl? 

Pearls are natural gems produced by the pearl oyster and the freshwater pearl mussel. Although other kinds of mollusc can produce a pearl, these have little value as they are not composed of nacre (the same substance as mother-of-pearl). Nacre is secreted in response to a microscopic irritant in the mollusc’s soft tissue. The concentric rings of nacre around the particle create the particular iridescence of Pearls due to the way the overlapping layers of diffract light waves. A Pearl’s color is described in term of body color and overtone – the most common body color is white, though it can range widely, and the overtone is the color that seems to appear only on the surface of the Pearl.

Natural Pearls that form in the wild are rare, and therefore valuable, and Pearl divers have to open hundreds of Pearl oysters before chancing on a specimen. Although diving for natural Pearls still occurs in Bahrain and off the coast of Australia, today’s Pearls are largely cultured, making them much affordable: an artificial nucleus, such as a round shell bead, is placed in the oyster or mussel for the nacre to form around. Freshwater Pearls are cheaper because the freshwater mussel can produce up to 20 Pearls at a time, whereas the smaller saltwater oyster can create just one. Saltwater Pearl are differentiated by region: South Sea Pearls are most valued due to their size, Tahitian Pearls are next for their colors (black among them), with Akoya being the least prized, being the most common.