PEARL TERMINOLGY

NACRE

Nacre, also known as mother-of-pearl, is the basic substance which is secreted by oysters and mollusks to form the inside of their shells. When nacre secretions are deposited around a foreign substance which has invaded the mollusk's body, they build up to form a pearl.

Nacre is composed of layers of calcium carbonate (in a crystalline form) and conchiolin (an organic protein substance which provides bonding). The specific luster, iridescence, and coloring of nacre -- and, therefore, of any pearl which it forms -- depends on the number and thickness of the various layers, as well as on whether or not the layers overlap one another.

MOTHER-OF-PEARL

Mother-of-pearl is the basic substance which is secreted by oysters and mollusks to form the inside of their shells. It is the same substance which forms pearls.

Until it was replaced by plastic in the mid-20th century, mother-of-pearl was also used to produce shiny buttons for clothing. This was the case in Broome Australia, a well-known South Sea pearl producing area. Before South Sea pearls became the area staple, this small town thrived on the Pinctada maxima mother-of-pearl business.

Mother-of-pearl is now used extensively as the nucleus in pearl cultivation. The shell of a mussel is cut into squares and then run through a process which rounds the pieces into beads. These beads are then implanted into the oysters which then secrete nacre upon the mother-of-pearl beads to form the cultured pearl.

Imitation pearls are artificial, manufactured "pearls". As such, they have no real value as a gemstone. Imitation pearls can be made from glass, ceramic, shell, or even plastic. The bead is then coated with varnish and/or other materials in order to produce a pearl-like luster and iridescence.

Imitation pearls are generally marketed under descriptive terms such as "faux," "simulated," "artificial," or "man-made." Sometimes regional names are also used: "Mallorca pearls," "Red Sea pearls," "Laguna pearls," etc. In the United States, it is considered a deceptive trade practice to market imitation pearls without clearly identifying them as such.

A common test to determine whether a pearl is genuine or imitation consists of scraping the pearl gently across one's teeth. Imitation pearls feel smooth to the tooth, while genuine pearls feel slightly gritty or abrasive due to the crystalline structure of the nacre.

A 50X magnifying lens will also show you a nonsmooth surface of a real pearl.