Detecting Golden Pearl Color Enhancement

When the first warnings about color enhancement of golden South Sea pearls came out five years ago, fear struck the South Sea pearl industry. Some of the new enhancement methods for golden pearls were nearly undetectable, leaving dealers and retailers guessing how many pearls on the market were treated and wondering whether golden pearls were going to be the gem world's next disclosure scandal.

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HomeLearning CenterJewelry MakingGemologyPearlsDetecting Golden Pearl Color Enhancement
By Suzanne WadeMore from this author

NEW YORK - When the first warnings about color enhancement of golden South Sea pearls came out five years ago, fear struck the South Sea pearl industry. Some of the new enhancement methods for golden pearls were nearly undetectable, leaving dealers and retailers guessing how many pearls on the market were treated and wondering whether golden pearls were going to be the gem world's next disclosure scandal.

Five years later, the news is mixed. On the plus side, recent research breakthroughs have made it easier for laboratories to detect treatments. Both the Gemological Institute of America (GIA) Gem Trade Laboratory and the American Gem Trade Association Gemological Testing Center (AGTA GTC) report that they can usually identify both treated and natural color pearls.

"In most cases we are able to make a decision," says Tom Moses of the GIA Gem Trade Lab in New York. "There are some instances where we are not able to, and we would still say the color origins are currently undetermined…. but we are pretty confident that we are able to detect at least most of the treatments."

Moses notes that although keeping up with the ingenuity of treaters can be difficult, there are a limited number of possibilities for altering the color of a pearl in a way that won't arouse suspicion. "There are a number of agents that can be used to make [golden] colorations, but it's still a limited range," he says. "The idea is to replicate a color appearance that is desirable and also overlaps the best colors that are produced naturally. So there's a kind of natural governor in there for the treaters. They don't want to create something unnatural. It would not be desirable, and it would be readily detectable."

By far the most common way to create golden pearls is by dyeing; they may also be heated. While dyeing can often be detected by looking for unusual color concentrations in surface defects or around drill holes, heat treatment requires more sophisticated equipment. Laboratories generally use techniques like ultraviolet spectroscopy and observing fluorescence.

Advances in technology have made gemological examination faster and more accurate, says Ken Scarratt, head of the AGTA GTC in New York. "The main technology we've relied on [in detecting treated pearls] is UV spectroscopy, and the main problem is the length of time it takes to take a spectrum of a single pearl, especially when there may be 50 or 100 in a necklace," he explains. "That has been largely overcome [by improvements in technology], and we can get the UV Vis spectra in just a matter of seconds for each pearl," as opposed to several minutes per pearl using older equipment.

While the labs are confident in their ability to detect treated golden pearls, they also say they see very few of them. "We really haven't seen that much of [heat treated golden pearls]," says Scarrett. "It may occur, and does occur, but we haven't seen very much of it."

"There are not too many [treated pearls being submitted to the GIA]," Moses concurs. "But we don't see too many necklaces or loose golden cultured pearls in general. Although clearly [golden pearls] have gained in popularity over the last number of years, it's still rather small numbers."

Dealers at the high end of the market also say that they see very few treated golden pearls. "I've heard that one needs to be careful, but in terms of actually seeing them, [it hasn't been a problem]," says Arman Asher of Albert Asher south Sea Pearl Co. "[Retailers] are relying on me that I guarantee it's an untreated product, and I rely on [those] I purchase from. It's a matter of trust; however, it's also a matter of whom you have done business with. I'm relying on the fact that my farmers are not going to take the chance [of ruining our relationship by slipping me treated pearls]."

"Sometimes I definitely know [the pearls have been treated], and other times I'll have my doubts," says Alex Vock of ProVockative Gems. "[When that happens], I'll tell the person, 'I'm going to buy this pearl, but you are going to put on the invoice that it's natural color,' and once *in a while, I'll have [the pearls] tested [at a lab]. I think most dealers are honest about it. I think there are a few [who aren't], but I don't think somebody like myself is going to try and sell enhanced as natural. I think it's more likely when [a dealer is] selling pure price points."

And that's the rub. While both farmers and wholesalers at the high end of the pearl market have their reputation to worry about and a higher probability of having their pearls sent to a laboratory at the commercial end of the market, it's a whole different game.

"We've been working on our first golden pearl pricing charts, and we found we did run into some difficulties in trying to get any consistency in pricing for the material," says Stuart Robinson, gemstone editor for The Guide. "We found that once we started to limit ourselves to better known American dealers, we were able to find better clarity in coining up with what the numbers looked like. So I think there is some influence [on prices] in far Asian markets with treatments, because we did see some golden pearls that appeared to be significantly less money than they technically should have been, and I think the fact that they were likely treated was the logical explanation for that."

To some observers, there are more golden pearls being offered on the market than an increase in fanning can explain. "Fifteen years ago, if I went to the international fair in Basel, or anywhere else in the world, I might see five golden pearl necklaces in the entire show," says gemologist Antoinette Matlins, author of The Pearl Book. "Eight years ago, I saw a large number of yellows and goldens. But I couldn't get over how many I saw at the JA and JCK shows recently. It's true that Indonesia and the Philippines have begun to produce far greater quantities of pearls than had been the case 15 or even 10 years ago … but I'm not confident that there is a large quantity of natural yellows in the sizes I'm seeing. I'm not saying definitively that these large size pearls are more likely to be treated, but I think we have to ask the question."

Color treated pearls are more common in Asian markets, claim pearl dealers. "In Japan, Hong Kong, and Korea, there's definitely demand for treated goods," says Vock, "They're willing to make the tradeoff between enhancement and price."

Unfortunately, those markets aren't always noted for their commitment to disclosure, especially when dealing in lower priced goods. "I think in Asia, [disclosure] is a problem," says Vock. "In the United States, it's not much of a problem. I'm sure it happens, but I don't think there's a lot of abuse. In Asia, they're a lot less careful. If they can sell something cheaply enough, they're not remorseful about [not disclosing]. They kind of feel if it's cheap enough, it doesn't matter."

Wherever they originate, commercial quality golden pearls are sold in sufficient quantity through a sufficiently convoluted supply chain that by the time they reach the end consumer, there are no guarantees. None of the suppliers, analysts, or laboratory gemologists interviewed for this article was willing to even venture a guess as to what percentage of those pearls are treated.

As a result, it's still "buyer beware" when purchasing golden pearls. A telltale sign is cost, especially when the price seems too good to be true.

"If you know the market for a good quality, golden 15 mm pearl should be around $3,000 to $4,000, and instead you're seeing it at $400 to $500, that should be a red flag to see what's going on," says Asher.

And for many retail buyers, price may be the only clue that something isn't quite as it should be. "I suspect somebody who is very knowledgeable would look at a necklace [of treated goldens] and say, 'There's something wrong about this,' and they'd probably be right," says Moses. "But for most people, I doubt they'd have any idea."

As with all gem treatments, the best defense against being sold something you didn't bargain for is doing business with a reputable dealer.

"I believe the most important thing retailers can do is to know whom they're buying from," says Asher. "By all means, if you have any doubts, say, 'To your knowledge is there any treatment or any possible treatments [used on these pearls], and will you stick behind it?' If something is found, are you going to be able to come back [to the dealer]? They need to stake their reputation on it."

By Suzanne Wade
© Colored Stone – 2003
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Suzanne Wade

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