When blue sapphires with unusual color distributions showed up in the market recently, gem labs shifted into overdrive to identify them. Tens of thousands of dollars were spent on secondary ion mass spectroscopy (SIMS) analysis and overseas expeditions, and gemologists spent a great deal of time and effort to determine if yet another troublesome enhancement had been set loose to bedevil the market. What they learned was that a lone treater in Sri Lanka was using a new furnace in a simple, ingenious, heat-only process. When a recent JCK Retail Panel questionnaire asked retailers if they cared whether a sapphire had received low-heat treatment vs. high-heat treatment, 95% said “no,” it didn’t make a difference. “A treatment is a treatment,” say retailers. “It’s still enhanced,” whether it’s “light heat” or “high heat.”
Why is there a disconnect between the labs’ view of corundum treatments and retailers’ view of the issue? Are lab gemologists overreacting? Or are retailers too nonchalant—or ignorant—about enhancements?
In fact, there’s a big difference between enhancements produced by low heat and those produced by high heat, because there are big differences in the original material. Making a nice transparent, healed, salable gem from Mong Hsu ruby (a.k.a. fish tank gravel) is different from taking a nice-quality but weak color Madagascan sapphire and simply boosting its color.
This raises more questions: Do retail jewelers know what happens inside a gem during low-temperature vs. high- temperature heating? Do retailers know their heated Mong Hsu Burma rubies—purchased for hundreds of dollars—used to look like fish tank gravel? Do they care? Should they?
Here’s a point to keep in mind when considering the answers: When thousands of carats of “padparadschas” showed up in the Thai and Japanese sapphire markets, the gem labs spent a great deal of time, money, and effort to figure out how these stones were being enhanced. And while they couldn’t prevent a major disaster in the Japanese market, they did save the U.S. market from serious problems.
Identification vs. disclosure. For gem labs to provide the industry with the information it needs for full disclosure, they must first identify what is happening inside a stone. Treaters don’t provide reliable data about their processes, so scientists and gemologists work backward to find answers. And that means pooling the chemistry and physics brain trust, gemological talent, high-tech testing equipment, time, and money.Enter the Sapphire Group, the scientists and gemologists who helped crack the major sapphire identification mysteries in the past few years. Among them are Dr. John Emmett (Crystal Chemistry), Matt Hall (GIA), Shane McClure (GIA), Tom Moses (GIA), Prof. George Rossman (Cal Tech), Ken Scarratt (AGTA), Chris Smith (GIA), and Dr. Wuyi Wang (GIA).
While retail jewelers sell sapphires as “natural” or “treated,” the Sapphire Group must identify the treatment, its effects, whether it’s permanent, and what—if anything—has been added onto or into the stone. For example, as long as there’s a significant price difference between “traditionally” heat-treated stones and “bulk lattice diffusion” treated stones, there will be a need for detailed identification.
Usually, examination of inclusions will reveal whether or not the gem has been heated. And with close to 99% of all sapphires being heated, one should be able to make that identification fairly readily. Because most sapphires are cooked at temperatures approaching 1,800ºC, inclusions look damaged or melted, making them easy indicators of heat.
Forgetting the lightly heated Madagascar stones for the moment, even if every sapphire could be identified as having been cooked, for the labs, just saying “heated” is not enough. They must determine whether additives were used, whether those additives helped alter the color, and if so, whether the color change is permanent. This is the difficult—and expensive—part.
So it was with the latest Sri Lankan blue sapphires. Using every scientific tool at hand, the Sapphire Group found no evidence of beryllium or any other additive. After the preliminary tests using laser ablation found no evidence of beryllium, and gemological examination proved there was no synthetic overgrowth, the focus turned to methods of heating. So it was up to Emmett and Rossman, chemist and physicist, respectively, to figure out the mechanics of how and why this color zoning was being created.
Although they met with the man who was responsible for all of the new treated sapphires, Emmett knew the treater’s explanation would be of little help. Knowing that oxidation heat can remove color centers, Emmett set out to design a heating technique for removing a specified depth of color from the surface layer of a synthetic blue sapphire sample. His experiment worked, and he solved the mystery.
“It’s a reaction front process,” says Rossman. “We call that a trapped diffusion process,” Emmett adds.
Gemologists also struggle with nomenclature. The terminology for beryllium treatment has changed from “diffusion treatment” to “surface diffusion” to “bulk diffusion” to “bulk lattice diffusion” and now to “lattice diffusion.” Whether the new enhancement is called a “reaction front” or a “trapped diffusion process,” it’s still a color change that dealers now know is caused only by heat, not by an additive like beryllium.
Prices right. The relevance of all this to retailers is that treatments determine corundum prices. There are five treatment-defined categories of corundum that affect price and must be disclosed:
Unenhanced (not alwaysidentifiable)
Lightly heated Madagascar material (no possibility of fissure healing; not always identifiable)
Heated (identifiable); heated without flux (not identifiable)
Heated (identifiable); heated with flux (not always identifiable)
Heated with an additive such as beryllium or titanium (and with flux; identifiable).
But when we posed four sapphire pricing options to the JCK Retail Panel and asked their preference, nearly 50% opted for the simplest, a two-tiered category that specified only “natural” and “treated” as categories. Slightly more than a quarter of respondents (28%) chose the three-tiered system (natural, heated, and lattice diffusion), 9% chose the four-tiered (natural, traditionally heated, high heat, and lattice diffusion), and 13% chose the five-tiered system (natural, traditionally heated, high heat with no evidence of healed fissures, high heat with healed fissures, and lattice diffusion). Clearly, retailers prefer to keep pricing and disclosure simple.
When asked if they believe treatments will destroy the sapphire market, 85% of our retail panelists said no. “Look at conflict diamonds,” wrote one panel member. “In the press for a while—and now hardly at all. Same thing happened with emeralds a couple of years ago.”
Nor have enhancements affected retail jewelers’ buying habits. Over 70% of retail panelists said that they have not changed their buying habits, even after the recent revelations of a new blue sapphire enhancement. According to the labs, gem identification business has increased, yet only 24% of our panel members say they buy sapphires with gem lab reports.
Bottom line for retailers. This issue will only become more complicated, and retailers need to be prepared. Consider these suggestions:
Always ask your corundum suppliers what enhancements have been done and what enhancements might have been done. Wholesalers have a stake in proper pricing and disclosure, so you have a reasonable expectation that they will be honest with you. But get the answer in writing anyway.
If your supplier can’t tell you what enhancements were done, learn to identify it yourself or send it to a lab.
If a stone has no gem report and you have to send it to a lab, be prepared to pay for the report.
Be prepared to wait (up to three weeks) for a report.
Understand that labs can’t always identify enhancements.
Make an arrangement with your suppliers by which they agree to take back any stone that, based on lab results, you don’t want.
Always make proper disclosure to your customers. Be honest but avoid scientific minutiae, and don’t use negative terminology.
Stay on your toes. Scrutinize every stone and ask questions. (Two questions that should have been asked back in 2000: “How come so much padparadscha sapphire has suddenly appeared on the market?” and “Where is this new yellow-sapphire mine?”)
Protecting the trade from unscrupulous treaters and dealers is a constant battle for the labs, and as treatment techniques advance, so does the science of gemology. Laboratory gemologists now are required to understand a wide range of scientific techniques: infrared and RAMAN spectroscopy, laser ablation – inductively coupled plasma – mass spectrometry (LA-ICP-MS), laser-induced breakdown spectroscopy (LIBS), and secondary ion mass spectroscopy (SIMS).
If it weren’t for the major independent gem labs, U.S. retailers, like their Japanese counterparts, would be stuck with beryllium-treated sapphires identified only as “traditionally heated.” Looking to future high-temperature enhancements, Emmett warns, “If we don’t keep up with the identifications of the treatments, you will soon be selling synthetics.”
So, maybe it’s time to take a lab gemologist to lunch. It’s a healthy way to support your local laboratory.