Dyed or Irradiated Cultured Pearls

September 1998

For Your Staff:Selling Treated Gemstones

Dyed or Irradiated Cultured Pearls

Most cultured pearls owe their luminous beauty and exotic colors to a special step or two taken after normal processing. Here's how to tell your customers about these enhancements

Cultured pearls form in a mollusk with the aid of humans. The process, patented in Japan early this century, involves implanting a mother-of-pearl nucleus in a mollusk.

The mollusk reacts by secreting nacre, a lustrous substance that builds up in layers around the nucleus, which usually is rounded.

Nacre is what gives pearls their natural color, generally pink, white, silver, gray, yellow, brown or gold. This "body" color is often complemented by a rainbow iridescence called "orient."

Introducing Color Enhancements
Sometimes, human ingenuity steps in to enhance the natural color of a pearl. Here's how to introduce the topic:

  • Pretreatment. Most pearls – including cultured saltwater, freshwater and South Sea – are bleached to lighten uneven dark areas that may appear under the nacre. This is permanent, provides a more uniform appearance and prepares the pearl for steps that can enhance the color.
  • Dyeing. Because pearls are porous, they often absorb human oils, makeup and perfume, which can stain. In fact, pearls are soft, porous and accepting to all contact with natural and chemical substances, such as dyes. Pearl treaters take advantage of this porosity to achieve finer, more uniform colors with natural extracts and inorganic and/or chemical dyes. Explain to your customer these dyes can fade over time. But stress the positive: the fact they make matched strands easier to create and more affordable.
  • Irradiation. Gamma-ray irradiation darkens the nucleus and results in darker pearls, sometimes dark enough to resemble natural color black South Sea pearls. The advantage, of course, is they can be sold for much less. Irradiation also enhances orient (the display of iridescent colors) in some pearls. In either case, the pearls retain no radioactivity, thus, the enhancement is considered harmless. Most experts believe this treatment is permanent.

Special Care
Pearls (cultured and natural) are quite soft, with a hardness of 2.5 on the Mohs scale – among the world's softest gems.

What's more, bleaching can make them brittle, so they should not be used in jewelry prone to knocks or scratching. Neither should you or your customers place pearls in an ultrasonic cleaner. Instead, clean them carefully with a moistened cotton cloth with no soap or detergent.

Selling Advice
It's difficult to tell whether a cultured pearl's color is natural or the result of dyeing or irradiation. Even experts have to rely on expensive – and often destructive – tests to determine enhancements conclusively. It's best to tell a customer her cultured pearls are enhanced to make the color more attractive unless you know and can explain conclusively (perhaps enlisting the help of your store's gemologist) that they're not.

Learn your store's policies concerning the disclosure of pearl enhancements. And read the Federal Trade Commission Guidelines concerning natural and enhanced pearls.

Additional Reading

The Pearl Buying Guideby Renee Newman, International Jewelry Publications, Los Angeles, CA.
Pearlsby Fred Ward, Gem Book Publishers, Bethesda, MD.
Gem Identification Made Easyby Antoinette Matlins, Gemstone Press, Woodstock, VT.
GIA's Gem Reference Guide,Gemological Institute of America, Carlsbad, CA.
AGTA Source Directory,1997/1998 Edition [contains Gem Enhancement Manual], American Gem Trade Association, Dallas, TX. AGTA Gemstone Enhancements,What You Should Know,American Gem Trade Association, Dallas, TX.
Gemstone Enhancementby Kurt Nassau, Ph.D., Butterworths, Stoneham, MA.

– by Robert Weldon, G.G.

It's difficult to tell whether a pearl's color is natural or the result of dyeing or irradiation. This collection of Chinese cultured freshwater pearls (from left) comprises dyed multicolor round, dyed mauve rondelle, natural white coin, dyed multicolor peacock, natural white bleached, irradiated silver rondelle, dyed multicolor peacock, dyed coffee brown round, irradiated gold coin and irradiated golden rondelle. Gems courtesy of King's Ransom, Sausalito, CA.

 

 

 

 

 

 Legal Considerations

Dyeing pearls is not considered a permanent enhancement because the color can fade over time. This is a clear case when enhancement must be disclosed to the consumer. This may make you uncomfortable at first, but it's better to explain now than deal with a complaint or lawsuit later.

In addition, even though most experts believe the effects of irradiation and bleaching are permanent, it's best to disclose them also because customers could feel deceived or claim in court they would not have bought any pearl had they known it was enhanced. (Note that in the language of the FTC Guides for the Jewelry Industry shown at right, irradiation is listed as a non-permanent treatment, which is true for certain gems.)

The FTC Guides pertaining to pearl enhancements read:

"It is unfair or deceptive to fail to disclose that a gemstone has been treated in any manner that is not permanent or that creates special care requirements, and to fail to disclose that the treatment is not permanent, if such is the case. The following are examples of treatments that should be disclosed because they usually are not permanent or create special care requirements: coating, impregnation, irradiating, heating, use of nuclear bombardment, application of colored or colorless oil or epoxy-like resins, wax, plastic, or glass, surface diffusion, or dyeing. This disclosure may be made at the point of sale, except that disclosure should be made in any solicitation where the product can be purchased without viewing (e.g., direct mail catalogs, on-line services), and in the case of televised shopping programs, on the air. If special care requirements for a gemstone arise because the gemstone has been treated, it is recommended that the seller disclose the special care requirements to the purchaser."

 

 



Copyright © 1998 by Bond Communications.


 

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