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
- 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.
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.
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
- 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,
- 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,
- Gemstone Enhancementby Kurt Nassau, Ph.D., Butterworths, Stoneham,
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.
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.