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Beryllium-Diffused Blue Sapphire?

April 2006

 
 

Gem dealers in Bangkok, Thailand, are reacting to concerns that beryllium diffusion is being used on blue sapphires.

Beryllium diffusion typically brightens the color of ruby or sapphire, making a stone more yellow, orange, or red, depending on the original color. Because the color change can go all the way through the stone, the treatment is more difficult to identify than traditional diffusion, which is an easily-detected surface treatment. When beryllium diffusion was first introduced to the market in 2001, uncertainty about disclosure created a controversy that led to a sharp drop in prices for the diffused stones. Today, beryllium-diffused corundum sells for a fraction of the price of its natural or heated counterparts.

Adolf Peretti, director of GemResearch Swisslab (GRS) — which has laboratories in Bangkok; Lucerne, Switzerland; and Colombo, Sri Lanka — reported in early 2006 that they have been seeing an increasing number of beryllium-diffused blue sapphires. A report on the GRS site said that well over 100 beryllium-diffused blue sapphires have been submitted to GRS laboratories since November 2005, the majority of the stones in the 5- to 10-carat range.

Peretti said he has some theories about how beryllium — which usually makes a sapphire yellower, and therefore worth less on the market — could be used to produce a better blue or enhanced clarity, but prefers not to discuss them pending consultation with other experts.

"The addition of beryllium will not produce a blue color in corundum. However, as the research of Dr. John Emmett and others has shown, a blue sapphire with a concentration of titanium higher than the combined concentration of magnesium that is inherent in the stone and the beryllium that is introduced may remain blue after beryllium diffusion," said Christopher Smith, director of identification services at the GIA Gem Trade Laboratory in New York City. "With this knowledge in hand, to date there are three potential reasons why beryllium could be encountered in blue sapphires. One relates to the original time when they were treating these stones to produce padparadscha colors. During a standard run when treating a large number of samples, a certain number of those stones remained light blue because of the inherent chemical composition and the amount of beryllium that entered the lattice. As time passed, another option includes inadvertent contamination," which could occur if blue sapphires were heated using standard techniques in the same furnaces used for beryllium diffusion, without changing the internal components. "Another is that beryllium could be intentionally added to lighten a darker stone. In some of the information we have collected, at least in part, beryllium diffusion is being done intentionally to try to lighten stones that are over-colored or dark."

Peretti believes the treatment is intentional, at least in most cases. "GRS placed an order for beryllium-treated [blue] sapphires on the market, and received — within three days — two lots. All of them were beryllium-treated homogeneously all over the surface, and with the same concentrations at levels known previously for other beryllium-treated fancy sapphires. Beryllium is diffused throughout the entire body of the sapphire, which requires extensive heat-treatment with beryllium, on the same level known for beryllium-treated yellows.

"There is currently a market price difference between samples heated with conventional methods and beryllium-treated sapphires," Peretti continued. "Conclusions on intentions of other people and companies are not up to us to answer."

Dealers in Bangkok confirm that the price difference between blue sapphires that have been beryllium-diffused and those which haven't is around 30 percent.

The issue has caused a storm of controversy among dealers in Bangkok, some of whom were badly burned when the original controversy over beryllium-diffused sapphire erupted in 2001.

Pornchai Chuenchomlada, president of the Thai Gem and Jewelry Traders Association (TGJTA), told Colored Stone that they have had three meetings with the Chanthaburi Gem & Jewelry Association (CGA). Chanthaburi is the city in southeastern Thailand where the bulk of the beryllium diffusion is done. "They are always finding new ways to burn [corundum], and they found another new technique," he said.

Following these meetings, he continued, the CGA has agreed to either disclose which sapphires have been beryllium diffused or stop the treatments altogether.

How much beryllium-diffused blue sapphire may already be on the market is still in question.

"We had started routinely testing for beryllium with any sapphire, including blues, if they revealed evidence of extreme thermal alteration due to very high temperatures and/or extended periods of time, since the original studies [several years ago]," said Smith. "From the stones that have been submitted by the trade, we have yet to identify any beryllium-treated stone."

Lore Kiefert, director of the American Gem Trade Association's Gem Testing Center (AGTA GTC) in New York City, said that she also has not seen any beryllium-diffused blue sapphire pass through their laboratory, although the AGTA GTC only tests for beryllium at the client's request.

"The stones that are out now make it necessary to test all blue sapphires [which have been heated at high temperatures]," she commented. "However, there is no need to panic and create a frenzy in the sapphire market. From what [various researchers have] found out, and we could also imagine, the process is quite complicated and takes a long time. . . . Therefore, it is not likely that many heaters will follow that path."

The beryllium-diffused blue sapphires can be identified with the same high-tech techniques already in use to detect beryllium-diffused sapphire in other colors. At press time, gemological laboratories internationally were cooperating to discover other identifying characteristics. Evidence of heating at extremely high temperatures, which can produce distinctive inclusion patterns inside the stone, is one clue that gemologists look at. However, it is possible for a sapphire to have such inclusions without containing beryllium.

"We're still in the investigatory phase," said Smith. "We don't know the scope of what may be available in the market, and we don't know the range of characteristics they may display or possess. However, as this information becomes available, we will be informing the trade." Until more is known, he joins gemologists around the world in urging wholesalers and retailers not to overreact or jump to conclusions.