The Cultured Pearl The Buying Guide

Getting to know Gems
How to select, buy, and care for, and enjoy Pearl Jewelry

The difference quality makes
Artificial enhancement used on lackluster pearls

With all things beautiful, rare, and costly, humankind tries to improve, imitate, duplicate. It has been this way since time began. Today virtually all colored gemstones are imitated, duplicated, and improved, and cultured pearls have not been ignored. As with other gems, some of the methods used are considered “acceptable” while others are not. It is important to be aware of the types of treatments being used, what is acceptable and what is not, and how they affect the final pearl product in terms of appearance, cost, and, most of all, durability.

All pearls are processed after removal from the mollusc. Routine processing will not harm them, and usually involves little more than washing to remove odors and residues from the pores of the pearl’s surface. This can be accomplished with mild sudsy warm water and a mild abrasive such as salt. The pearls are put into “tumbling” drums with the solution, and tumbled together for a brief time.

Routine tumbling is performed by all cultured pearl producers, and is perfectly safe.

Excessive processing and treatment can harm pearls

Certain types of cultured pears are routinely subjected to extensive processing and various other treatments that may have an adverse effect on durability, and thus to the life of the pearl. These include extensive tumbling, often with wax or polishing compounds, coating pearl surfaces, chemical bleaching and dyeing. Here are some practices to be aware of and to guard against:

Enhancement of luster and surface perfection

Since lustrousness is so desirable in a pearl, and because it is usually very low in poor quality pearls, some producers employ artificial methods along with routine processing to create an impression of lustrousness. The following enhancements result in a temporary surface shine only.

- Extensive tumbling is used by some producers to remove unsightly surface blemishes and dark spots, and to improve the shape of the pearl. Nacre is durable because of its very compact structure, but it is not very hard. Depending upon the tumbling process used, some of the nacre may actually be wearing off as the pearl is being tumbled; the longer the tumbling, the greater the amount of nacre removed.

- Buffing is used by some producers to remove blemishes, improve the shape, and to add a surface shine. Here the pearls are “buffed” against a rapidly moving abrasive wheel with a very mild abrasive compound. It is very effective, but removes more nacre than simple tumbling. Beeswax and other polishing compounds are sometimes used while tumbling or buffing; beeswax is soft and won’t remove the nacre; harder compounds will remove nacre.

- Tumbling with beeswax is done primarily to improve the pearl’s lustrousness. Wax is melted in very hot pans and then bamboo chips are added. After the chips have become saturated wit beeswax, they are placed together with the pearls in tumbling drums. As they tumble around together in the drum, a waxy costing is acquired by the pearls. Since the bamboo chips are softer than pearl, the pearls are not scratched or nacre thickness eroded. This wax coating imparts a lustrousness, but it is temporary and will wear off in a short period of time; and if you clean your pearls in an ultrasonic cleaner, nacre will wear off even faster!

- Extensive buffing with chemical polishing compounds is sometimes done to remove more unsightly surface imperfections and to increase surface shine. Chemical compounds create a longer lasting shine than wax, but it is still temporary and, even worse, these compounds often remove layers of nacre, reducing the life of the pearl.

- Coating with lacquer or “pearl-essence”; an epoxy and ground fish scale concoction used to create imitation pearls, to create a surface shine. Lacquer wears off quickly; pearl-essence may last longer.

In the case of poor quality mabe pearls, pearl-essence and dye are often applied to the inside of the pearl, just beneath the nacre (since mabe pearls are actually hollow blisters that are cut from the shell and then filled with another substance to increase durability, it is easy to coat the inside with pearl-essence prior to filling it).

This practice is not accepted as a fair trade practice and is considered fraudulent; nonetheless, it occurs. While there are some higher quality mabe pearls with thick nacre, especially South Sea mabe pearls, one must be on guard against mabe treated in this way because their thin nacre will peel and crack very easily. When buying mabe pearls, pay particular attention to lustrousness. However, you may not be able to recognize a pearl treated in this way. Should your mabe pearl begin to peel, or if it cracks prematurely despite proper care, we suggest to return it to your jeweler.

Any treatment that reduces nacre thickness is detrimental to the life of the pearl. Pearls that are buffed or tumbled extensively lose some of their nacre and are at greater risk of cracking and chipping. If nacre was thin prior to treatment, the result may be pearls with nacre that will more quickly wear off, leaving only mother-of-pearl beads.

Be especially careful not to to mistake shallow shine for the rich luster that indicates a deep, thick nacre. If in doubt, ask that the pearls be submitted to a laboratory for a report on nacre thickness.

Techniques to alter color

Whitening the color of pearls has taken place for centuries. In the case of natural pearls, however, it was a natural process whereby pearls were sun-bleached on rugs for a period of time. The rugs could be easily rotated to expose various parts of the pearl so color would be uniform. Many pearls today are also whitened, but normally the whitening process involves chemical bleaching. In addition to whitening, color is further enhanced by dyeing or other artificial techniques. Bleaching and dyeing is done to create continuity of color, which people have come to expect in cultured pearls as a result of advertising and promotion.

Today, most South Sea pearls, naturally black pearls from Tahiti and other parts of the South Pacific, and American freshwater cultured pearls are the only pearls being cultured that are not normally subjected to chemical bleaching and dyeing as part of routine processing.

- Chemical bleaching is done to make pearls whiter. This is now a common practice among many producers of cultured pearls.

This process is especially detrimental to thin nacre pearls because chemical bleaching reduces the hardness of the nacre, making the pearl softer and more susceptible to deterioration from normal wear. If the pearl has a good nacre thickness, this probably won’t seriously affect its durability; if the pearl has thin nacre, chemical bleaching will further weaken it.

All pearls with thin nacre must be bleached because the nacre is so thin that the brownish conchiolin shows through, creating an undesirable dark color; in thick nacre pearls, the dark conchiolin won’t show through so bleaching may not be necessary. (Remember that the oyster first produces a brownish layer of a substance called “Conchiolin” before producing the layers of white nacre that build up to give us the pearl.) To bleach pearls, they are first drilled and then submerged in a bleaching solution which takes the brownish color out of the conchiolin layer, thus whitening the pearl. Bleaching also produces a more uniform surface whiteness.

- Dyeing pearls to create a more desirable color is an increasingly common practice and goes hand-in-hand with bleaching.

The bleaching often results in a pearl that is too white, making it seem lifeless. The pearls are then soaked in a dye solution, usually pink, to give them a softer, warmer look that enhances desirability. naturally white pearls with a lovely pink or “rose” blush are very rare and highly prized; most of today’s pink-white (rose-white) pearls have obtained their pink color artificially through the dyeing process. It is usually easy to detect using the loupe.

Pearls can also be dyed other colors. Most pearls under 8 millimeters in diameter have been dyed black; most naturally black pearls are produced by a large variety of oyster is the South Pacific and start at about 8 millimeters in size. Many dyed black pearls have a different look from the natural, a look that suggests the use of dye; a “flat,” very uniform black coloration that lacks any iridescence or subtle shading and variation typical of naturally black pearls. They should cost a fraction of what naturally black pearls cost, and much less than good white pearls.

- Dyeing the nucleus to create “black” pearls is done on Akoya type cultured pearls.

While Japan is producing natural black cultured pearls, many gray to black cultured pearls under 9 millimeters in diameter contain a dyed nucleus; dyed with an organic dye, that is responsible for the color seen on the surface. This cannot be detected without sophisticated lab tests.

- Irradiation techniques have been used to artificially transform inexpensive, usually off-color South Sea pearls into black pearls to imitate the rare and costly naturally cultured pearls of the South Pacific.

While not commonplace, such pearls do appear in the market, so it is recommended that one submit any large black pearl represented to have natural color to a laboratory for verification.

A rich blue mabe pearl has recently entered the marketplace. An especially beautiful color, it is being sold as both natural and irradiated. In fact, it is neither; the blue comes from using a deep blue dome shaped plastic insert. These mabes are cut from the shell, and the very thin nacre cap is removed, and dipped in an artificial “pearl-like” coating to create the illusion of an iridescent lustrousness. The deep blue plastic dome is then reinserted, filled with epoxy, and glued to a mother-of-pearl backing.

- Silver nitrate solution is used in China, and so to a laser extent in other countries, to transform inexpensive, off-color pearls that resemble the rare and costly natural black cultured pearls of the South Pacific.

Use of silver nitrate solution is the most damaging of all treatments used on pearls, much more damaging to the pearl than chemical bleaching, making the nacre much softer and less durable. It reduces the pearl’s very resilience. Never buy pearls that have been treated with silver nitrate. Again, it is recommended that one submit any black pearl represented to have natural color to a laboratory fro verification.

There is nothing wrong with buying or selling color enhanced pearls as long as they are properly represented and appropriately priced. Such pearls should sell for much less than natural color cultured pearls.

Fine pearls: Beauty that needs no artificial enhancement

Overly short cultivation periods, excessive processing, and fraudulent treatment practices have been a source of intensifying debate and concern over past years. International pearl summits have focused heavily on these issues. As a result, an increasing number of producers have began to implement more rigid standards in the cultivation and processing of pearls, with Japan and Australia leading the way. The focus of the world’s leading producers is shifting from quantity to quality; the focus now seems to be on finding more effective ways to reduce risk, but to do so without reducing quality, beauty, and longevity of the pearl itself.

The future looks bright, but for the present you must remain attentive to quality differences. Insist on pearls with a rich, lustrous quality that assures you of thick nacre and, most of all, long lasting beauty and pleasure.

Pearl treatments and processing are meant to improve upon nature. With fine pearls, however, such efforts rarely improve them, and often diminish them. Fortunately, pearl producers are beginning to recognize this, and knowledgeable pearl connoisseurs are developing a greater appreciation for, and acceptance of, the little imperfections and differences that go hand-in-hand with any product created by nature. The lustrousness and soft iridescence of fine pearls; cultured or natural, has an allure of its own, a beauty that transcend minor “surface” imperfection!

Types of misrepresentation

Fine pearls, natural and cultured, are very costly. The finer and rarer, the more costly. As price and demand increase, however, so do incidents of fraud and misrepresentation. For this reason, one can not stress too strongly the importance of buying from a reputable, knowledgeable jewelers. Be wary of bargains and special “promotions” which may signal inferior quality pearls that will crack, peel, and lose their beauty very quickly. Here are some practices to be aware of, and to guard against:

- Selling as “natural color” pearls that have been dyed, irradiated, or treated with silver nitrate solution. As it is mentioned earlier, the color of pearls can be artificially enhanced or changed in a variety of ways. For this reason, when buying fine “natural color” pearls we recommend obtaining a laboratory report verifying that the color is natural.

- Selling lacquer coated pearls without disclosure. It is already mentioned that some pearls are coated with lacquer to improve lustrousness. Failure to disclose the fact that they are coated is unethical.

- Misrepresenting as “round: pearls, pearls that are not. Since shape is an important factor in valuing pearls, and round pearls are rarer and more costly than those that are not round, creating the illusion of “round” is sometimes done through clever setting or stringing. A lacquer coated filler can also be used to “round out” depression in single, larger pearls.

- Misrepresenting three-quarter pearls as full round pearls. This is done because three-quarter pearls are significantly less expensive than round pearls. The flatter side is concealed in the setting, often a large “cup” type mounting, The cup holds the pearl in such a way that the back of the pearl cannot be seen and the flat side is concealed, the cup itself completes the illusion of roundness. Mounting used to set fine round pearls normally use cups small enough to permit you see the full symmetry of the pearl.

Be specially careful when buying fine, round South Sea pearls because the difference in cost is dramatic. Many three-quarter South Sea pearls are being produced in the Philippines, and sold as fine round South Sea pearls, at greatly inflated prices. These may seem like “a good buy” to the unsuspecting. There is nothing wrong with buying three-quarter pearls; they can create a large, important look; as long as you know what you are buying and pay a fair price for it.

- Misrepresenting half pearls as round pearl. Half pearls, or hemisphere pearls, have a flat side where half of the pearl has been cut away to remove an unsightly blemish or defect. Natural half pearls were very popular for use in antique jewelry, especially in pieces requiring numerous small pearls, and are sometimes mistakenly identified as round natural pearls. Examining the pearls with a loupe will usually reveal the flat back.

- Filling surface pits. This sometimes done to conceal a a particularly unsightly “pit” or hole in the pearl’s surface. The pit is filled with epoxy; the epoxy is then covered with tinted lacquer or pearl-essence. “Second hand” pearls that were damaged are sometimes repaired in this manner.

- Misrepresenting imitation pearls as cultured or natural pearls. This may be accidental or deliberate. Many people erroneously assume that pearls that have been passed down through many generations, or been in the possession of wealthy people, must be “real.” Unfortunately this is not the case; imitation pearls have been made for hundreds of years and anyone, including royalty, can own imitation pearls. It is usually a very easy thing to tell the real from the fake with the simple tooth test.

- Misrepresenting cultured pearls as “real” or “natural” pearls. If buying pearls that are represented to be natural, be sure they are accompanied by a laboratory report verifying this to be true (X-ray examination is required).

- Misrepresenting mollusc “hinges” as “natural” pearls. Some “natural” pearls are nothing more than the nacre coated “hinges” of a mollusc shell that has been cut and polished. When buying natural pearls, be sure they are accompanied by a laboratory report.