Why Some Pearl Necklaces May Not Last

Lately, pearl jewelry is becoming a hot fashion accessory, with pearl-sporting stars like actress Sarah Jessica Parker contributing to the sizzle.

But if you buy a string of cultured pearls at some national jewelry store chains, they might not last as long as you think, one jewelry expert told Greg Hunter, consumer correspondent for ABCNEWS' Good Morning America.

"It will change, it will deteriorate into worthless shell beads because the pearl coating basically comes off," said Antoinette Matlins, a gem and jewelry expert and author of The Pearl Book: The Definitive Buying Guide. "It won't be a pearl."

As an experiment, Matlins and a Good Morning America producer went pearl shopping at three jewelry stores that were part of national chains, and one department store. After expert gemologists examined the brand-new jewelry, they found three of the necklaces and one of the bracelets had pearls that were already chipping around the drill holes, where the pearls are strung together.

"Oh my goodness ... this is absurd," said Cap Beesley, president of American Gemological Laboratories in New York, who examined a pearl necklace that they had purchased for $464. The store, part of a national jewelry chain, had marked it down from $999.

When Beesley looked at the necklace under a microscope, the gemologist found several chipping pearls, which seemed to be missing large sections of nacre, the natural substance that from which pearls are made.

Pearls Are Big Business

Most pearls sold today are not the natural kind, but rather cultured pearls, grown on pearl farms.

Natural pearls form when an irritant — such as a grain of sand — gets into an oyster, prompting it to produce nacre, a coating substance that eventually forms a pearl. Such natural pearls are rarely found; the fine ones that do exist command staggering prices and are mostly owned by collectors or connoisseurs.

Since pearl cultivation started in earnest back in 1920, pearl farmers have been giving nature a little push to create pearls the same way that natural pearls form.

Technicians insert shell beads made of mother-of-pearl into live oysters. Because the mollusks consider the beads to be an irritant, they form nacre around it. Over a period of up to two years, this layer upon layer of nacre forms what the pearl farmers hopes will be a round, relatively blemish-free pearl.

But to meet the demand for pearls, some farmers remove the pearls from the oysters too soon, before the nacre coating has thickened, Matlins said.

"If the pearl coating is tissue-paper thin, it's going to peel off and leave just the bead," Matlins said.

A Disheartening Shopping Trip

At the first chain store, Matlins and the Good Morning America producer bought a $185 cultured pearl bracelet, a $285 cultured pearl necklace on sale for $199 and a $1,299 cultured pearl necklace. They were assured that the pearls would last. "Unless you beat the crap out of 'em, nothing is going to happen," the salesperson assured them.

At the second chain store, they bought a $699 cultured pearl necklace for $499.

"You should have them forever; you should be able to pass them down," the salesperson said.

At the third chain store, they were told that the would get a deal: a $999 cultured pearl necklace for only $464. They were assured that the coating would last.

"They are not going to peel unless you hit it on something or bang it around," the salesperson said.

Lastly, a national department store sold the producer and Matlins a $2,200 necklace for $913.

"Nothing is going to happen to these as far as peeling … ever," the salesperson said.

Chipped and Thin Pearls

Back at his lab, Beesley examined the pearl jewelry that Matlins and the Good Morning America producer had just purchased. The news was not good.

"Some of these are not fit for use — they are total, complete rejects," Beesley said, looking at one of the necklaces.

Under a microscope, one could see where the nacre in the $464 chain store pearl necklace was missing in some of the beads, and that a shell bead was visible underneath.

"It has the appearance of improperly fired pottery," Beesley said.

Experts also found that the pearls in the $185 dollar bracelet were chipping.

"You can see clearly the shell bead showing through, and see how much of that has already peeled away," Beesley said.

The $285 necklace had chipped pearls, and an exposed shell bead. When a pearl starts peeling to that extent, it can continue to peel, going through the rest of the pearl. The $699 pearl also had some pearls that were chipped and showed signs of visible peeling.

No Standards for Thickness

Unlike the tightly regulated diamond industry, the pearl industry does not have an official set of standards by which everyone who buys and sells pearls can measure them.

Since 1987, the Gemological Institute of America has used a grading chart that rates pearl thickness in millimeters from very thin to thick. Hunter picked out five pearls at random from the six samples to test them for thickness, a test that requires actually cutting the pearls in half.

Using a special optical microscope and computer that measures nacre thickness to 80-millionths of an inch, two out of the six samples measured were thin, while the other four were classified as very thin.

Tips for Pearl Buyers

When Hunter asked retailers about the pearls, they pointed out that they offer different quality pearls at different prices, so that you get what you pay for.

The Cultured Pearl Information Center in New York says consumers should not buy pearls that have a thin nacre, less than .3 millimeters, about the thickness of four $1 dollar bills. Some of the pearls that Good Morning America measured were thinner than the thickness of a single $1 bill. Experts also recommend that you don't buy pearls that already show damage.

You should check around the drill holes — where the pearls are strung together — for chipping, cracking and peeling. Experts say that if you see that, the problems may grow worse over time.

Although the Good Morning America experiment turned up some poor quality pearls, informed buyers can still find good quality gemstones, if they know what to look for.

The following tips are from Matlins' The Pearl Book: The Definitive Buying Guide.

Take time to visit fine jewelers who are knowledgeable about pearls, and will be able to show you a wide selection. For example, if you are looking at a pearl necklace, ask to see different necklaces that have the same size pearls, but are at different price points, so that you can see the difference in quality. To find a reputable jeweler, check with Jewelers of America, at www.jewelers.org.

Luster, the emanating glow that distinguishes pearls from other gems, is the most important quality, the one that can make up for a pearl that is small, blemished or perhaps not perfectly round. Thin or imitation pearls may have surface shine, but they do not absorb and refract rays of light in the same way a quality pearl does.

Examine the pearls against your neck and face to see if the color suits your skin, eye and hair coloring.

Ask if the color is natural, especially when buying colored pearls, such as gray, pink, blue or black . Artificially colored pearls should sell for much less.

Make sure that "genuine cultured" or "genuine natural pearls" is written on the bill of sale.

Matlins also suggests trying the "tooth test" to spot fake pearls. Run the pearl gently along the edge of your teeth, preferably the upper ones. Genuine pearls have a slightly abrasive or gritty feel, while fakes are slippery smooth.