Pearls are natural gems, created by organic processes in nature. An oyster covers an alien object with exquisite layers of nacre. In order to defend itself against this foreign body, the creature produces secretions to cover the external object. Many layers of this covering are cast off on to the irritant, making the latter smooth and round. A natural pearl is thus produced.

A cultured pearl, on the other hand, is formed by artificially introducing a foreign body called a shell bead nucleus, in order to get the oyster to produce a coating. In other words, a shell bead is placed inside an oyster, which is then put back into the water. When harvesting the pearls, the layers of nacre can be seen shimmering over the bead. The outer surface of a cultured pearl is made of concentric layers of calcium carbonate and other organic substances. A Japanese artist named Mikimoto first introduced the concept of cultured pearls during the 1900s. Once his concept was accepted, cultured pearls became the preferred and accepted option because pearl jewelry became more reasonably priced. Before that, natural pearls were rare and within reach of royalty only.

Fresh water pearls are cultured in China, using freshwater mussels. The waters of the south pacific are home to large oysters that produce the famous South Sea cultured pearls and the Tahitian black cultured pearls.

Cultured pearls, like their natural counterparts, can be identified by their textured surface, flawless nacre and soft iridescence. Cultured pearl earrings are a favorite for many reasons, because they are affordable and come in a wide range of prices and colors. Rose tinted cultured pearl jewelry is very popular, but black, grey, blue-green and golden are also considered exotic and classy.