The Jewelry Insider

June 10, 2008

Can a worm really turn into a pearl? follows the worm and

squeamishly uncovers how some of the little critters really do turn into perfect

It’s hard to believe that such a luscious, beautiful gem comes from such
humble origins.

Almost any shelled mollusk can, by natural processes, produce some kind of
‘pearl’ when an irritating microscopic object becomes trapped within the
mollusk’s folds, but virtually none of these “pearls” are considered to be

True iridescent pearls, the most desirable pearls, are produced by two groups
of molluscan. One family lives in the sea: the pearl oysters. The other, a very
different group of molluscs live in freshwater, and these are the river mussels.

A natural pearl starts out as a grain of sand or microscopic worm that works
its way into an oyster and cannot be expelled. To protect its soft body from
this irritant, the oyster secretes a smooth, hard crystalline substance called
nacre. Layer upon layer of nacre coats the foreign object and hardens,
ultimately forming a pearl. In general, the thicker the nacre, the richer the
“glow” of the pearl – which can greatly enhance its value.

early pearl gathering depended on divers braving the oceans’ depths to retrieve
these treasures, the vast majority of pearls today are grown, or cultured, on
pearl farms by surgically inserting a small shell bead, or nucleus, into the
mantle of an oyster.

Even though pearls are harvested en masse on pearl farms, producing a quality
pearl is an extremely rare event. It is estimated that half of all nucleated
oysters do not survive – and of those that do, only 20% bear marketable pearls.

When shopping for pearls, the five factors that determine value are luster
(surface brilliance); surface cleanliness (absence of spots, bumps or cracks);
shape (generally, the rounder the pearl, the higher its value); color (pearls
come in virtually every hue of the rainbow, and a few others, too); and size
(the average pearl sold is 7-7.5 millimeters, but these gems can be as small as
1 millimeter or as large as 20 millimeters).

Because pearls are soft, ranking only 2.5-4.5 on the Mohs scale for hardness,
they require special care. Natural oils from the skin, as well as hair spray,
lotions and cosmetics, can dull their luster. Like other jewelry, they should be
cleaned with a soft damp cloth and stored in cloth or cotton away from other
jewelry to prevent scratching. Also, avoid allowing your pearl to come in
contact with harsh chemicals, which can erode its surface. And if worn
frequently, pearl necklaces should be brought to a jeweler once a year for
re-stringing to prevent strand breakage.

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