Pearl Wisdom

Once pearls were considered far more valuable than diamonds, since only 1 in 10,000 oysters may contain a round natural pearl. In Roman times, pearls were so sought after and expensive that Julius Caesar barred women below a certain rank from wearing them. It wasn't until Kokichi Mikimoto, founder of Mikimoto pearls, successfully cultured pearls in the early 1900s that they could be easily matched and made into necklaces (before that, it could take up to 10 years to find enough matching pearls to make a strand). It was Coco Chanel who exploited the discovery of cultured pearls and probably did more than any other woman to give them a modern swing, piling them on and mixing real with costume.

These days real pearls are easy to find, especially on the Internet. But unlike diamonds, they do not have a universal grading system, so serious buyers must still rely on skilled eyes, which can take years to develop. Most experts warn against purchasing pearls sight unseen because of the seven factors one must consider when assessing their value: size, color, shape, luster, surface quality, nacre and how well they match.

Colors vary tremendously. Akoya pearls, prized for their bright whites and creams, have a warm hue, as do the larger South Sea pearls, which come in gold, silver and white, and freshwater mussels, available in a range of pastels. Tahitian pearls, which were not successfully cultivated until the 1970s, have cooler hues, like black, gray and green. Some pearls are shinier than others. "Luster is a matter of taste," says Tom Moses, senior vice president of the laboratory and research departments at the Gemological Institute of America, an educational group. "At the moment, in the U.S., pearls with high lusters are the most desirable. But in the 1950s a softer luster was more in style."

Size also matters. The larger South Sea pearls, typically 12 to 20 mm, tend to have a more satiny appearance, whereas the smaller akoyas, 7 to 9 mm, are prized for their quicksilver, mirrorlike sheen. To judge a pearl's luster, hold it under a light. If you see a bright, sharp reflection, the pearl has high luster and most likely a higher price tag.

It takes a surprising amount of skill to put together a well-matched strand, and that contributes to its price. Look for pearls that have few visible dimples, bumps or wrinkling. Decide whether you want to spend money on the more expensive perfectly spherical or symmetrical pearls or are willing to go for a more organic shape. After all, pearls are produced by nature, and nearly round pearls or organic shapes like baroque or semibaroque have character and may be easier on the wallet.