The Categories in a Nutshell

There are three types of pearls, natural, cultured and imitation:

* Natural pearls are created as a spontaneous response to a naturally occurring irritant in a mollusk. The mollusk makes the pearl by building layer upon layer of iridescent nacre to cover the irritant. Nacre is the same lustrous coating known as mother-of-pearl when it sheathes the inside of pearl-producing mollusk shells. The layers of nacre harden to form a pearl. Natural pearls are extremely rare. Hardly ever uniform in shape, natural pearls will feel gritty when rubbed against your tooth.

* Cultured pearls are created when an irritant (a piece of shell from another oyster or a round bead) is placed inside an oyster or mussel to instigate production of a pearl, which takes from three to five years. The thickness of the nacre is key to determining the value of a cultured pearl. If the luster is rich, the nacre is likely to be of top quality. High-quality cultured pearls have thicker layers of nacre that obliterate dark shadows.

* Imitation pearls (also called faux, simulated or semi-cultured) are made from glass, plastic or mother-of-pearl beads that have been dipped in a mixture of ground fish scales and lacquer or in a lustrous plastic coating. Good imitation pearls are made of glass beads that have been dipped in “pearl essence” enough times to fool the eye. Cheaper varieties are lighter because they are made from hollow-core plastic beads coated with a thin shiny surface. Shine is the inexpensive substitute for luster.