RAPAPORT... In influx of saltwater pearls, characterized by an almost perfect appearance and often accompanied by reports describing them as natural, is arriving at gem labs for certification, sent in by dealers uncertain of their origin. The Swiss Gemmological Institute (SSEF) reports receiving large quantities of these pearls that after tests — including X-ray radiography, X-ray luminescence, micro X-ray tomography and radiocarbon age dating — were identified in many cases as beadless cultured pearls, also called nonbead cultured pearls.
Dr. Michael S. Krzemnicki, SSEF director, believes the recent deluge of these pearls, with quality far better than that of many natural pearls, presents a danger to the natural pearl market. He says his lab is working with international trade groups and other gemological institutions to coordinate pearl testing and reporting standards.
“SSEF has been closely following the developments of the cultured pearl industry for years, especially concerning beadless saltwater cultured pearls,” Krzemnicki says. “We have committed extensive research to these developments and have introduced new analytical techniques to our pearl-testing services, such as micro X-ray tomography. With the sudden increase in the presence of this material on the market, we are adapting our pearl certification policy in an effort to protect the natural pearl trade.”
Krzemnicki says the pearls in question are byproducts of the production of beaded cultured pearls, described in the trade as “keshi.” Further, he explains, “A combination of internal and external features characterizes these pearls as cultured. Pearls are often button-, oval- to drop-shaped or baroque. Perfectly round or barrel-shaped beadless cultured pearls are rare.”
According to Krzemnicki, the most common internal feature is a small, curved dark line or larger curved cavity in the pearl’s center. Moreover, there is the presence of a round dark core of fine circular chonchiolin layers, often with one or more central nacre points, which may be misinterpreted as an indicator of natural growth.
These pearls are often intentionally drilled to remove their internal structure, which is the evidence laboratories use to determine origin, Krzemnicki adds, making it difficult for gemologists to offer a firm opinion regarding natural versus cultured.
Identifying the Difference
Nick Sturman, Gemological Institute of America (GIA) Laboratory, Bangkok, notes that natural pearls may show a diverse range of structures, starting from where an obvious nucleus is visible to examples where no clear internal structure is evident.
Sturman, who wrote on this topic in 2009 for GIA’s journal, Gems & Gemology, identifies a nonbead cultured pearl as one that forms “with the aid of human intervention, but without the insertion of a solid bead, and is, therefore, not classified as a bead cultured pearl or a natural pearl.”
“This intervention may be direct and intentional via the placement of tissue from a sacrificed donor mollusk into a living host mollusk, or indirect, via unintentional formation related to cultivation,” Sturman reports. “Most freshwater nonbead cultured pearls currently in the market are likely formed by the former process, whereas most saltwater nonbead cultured pearls are likely due to the latter.”
Noting that the problem of distinguishing nonbead from natural pearls “is something we have been monitoring for a decade or more,” Kenneth Scarratt, managing director of GIA Southeast Asia and director of the GIA Laboratory in Bangkok, says a move to high-definition, real-time microradiography equipment several years ago “provides us with better images for the analysis of pearls and allows us to electronically share images with, and gain the opinions of, researchers in other locations in an effort to protect all elements of today’s pearl market.
“Of course, instrumentation is only one element in quality pearl identification. Of equal, and often greater, importance is the depth of experience of those who interpret the images,” adds Scarratt, noting that the three senior members of the GIA identification teams have more than 75 years of collective experience in the field.
Against Lab Logic
James Peach, president of United States Pearl Co., Camden, Tennessee — cultivator of American freshwater pearls and the world’s largest producer of bead nuclei — believes the SSEF is off base in its reasoning, having no historical data on natural pearls to make a legitimate decision on origin.
“So the SSEF has decided that it can distinguish a wild pearl from a tame one?” questions Peach, who recently approached GIA with the idea of developing a pearl database to help the industry set more specific parameters regarding the origin of natural pearls. “The Swiss lab is making an assumption that natural pearls do not have a beginning, but whether a pearl is natural or cultured, all pearls have a nucleus.”
Peach also questions the industry definitions for natural and cultured pearls that specify that whereas a natural pearl is formed without human intervention in a wild oyster living in its natural habitat, any pearl stemming from a pearl cultivation farm is a cultured pearl — even if it forms accidentally, following a rejected bead or injuries during grafting.
Peach, who grew up pearl farming and is an avid collector of natural pearls, appreciates all types of pearls and feels the more pearls, the better. He notes that a cultured pearl can have a natural pearl growing with it. “Who’s to say it was the result of the cultivation process?” he asks. “All pearls that grow or form on their own should be considered natural — even if they grow during the farming process. Just because they grow on a pearl farm and not in the wild does not mean they cannot be natural.” And, of course, their natural status would enhance their value.
Peach believes that a greater supply of natural pearls will make the pearl world much more interesting. He hopes that as this issue is debated, it may lead to a discussion on how pearls are priced that is more about quality and size than origin, as that is what the average buyer can see and understand.
Article from the Rapaport Magazine - September 2010. To subscribe click here.