Foreign Affairs: Fracture healing/filling of Mong Hsu ruby
By Richard W. Hughes & Olivier Galibert
PICTURE THIS: a well-known European dealer sells a 2.5-carat Möng Hsu ruby to a major jeweler in Europe. This jeweler then sells the stone to a Japanese client through their Japanese subsidiary. The client now takes the stone to a gemological lab, which issues a report stating that the gem's fractures have been healed with a foreign substance. Now the fun really starts. Feeling cheated, the customer returns the stone and demands a full refund. Thus begins a lawsuit which involves several firms, spans two continents and is still snaking its way through the court system in France.
Today, courts are increasingly being called upon to arbitrate such disputes, largely because sellers have failed to disclose the flux healing of fractures in Möng Hsu ruby from Burma. The problem is a huge one, a corundum conundrum that will only escalate until the trade begins to enforce a policy of full disclosure of all gemstone enhancements. The following article examines the roots of the issue.
Möng Hsu is not Mogok
Mogok is not the only active ruby mining area in Burma. Stones from the Möng Hsu (pronounced 'Maing Shu' by the Shan; 'Mong Shu' by the Burmese) deposit, located in Myanmar's Shan State, northeast of Taunggyi, first began appearing in Bangkok in mid-1992. Since that time they have completely dominated the world's ruby trade in sizes of less than 3 ct. Indeed, 99% of all the rubies traded today in Chanthaburi (Thailand) are from Möng Hsu.
In terms of quality, Möng Hsu rubies cannot compete with Mogok stones. Before heat treatment, the Möng Hsu ruby is certainly an ugly duckling. There are two major problems. The first is dense silk clouds and a strong purplish color, making most stones look like low-grade, cloudy rhodolite garnet. This is mainly due to the crystal's unusual blue cores. Ordinary heat-treatment removes the blue, as well as removing silk, making the final product a rich, clear red. The market generally accepts such heated stones without a quibble.
This is not the case for the second problem. Most Möng Hsu stones are heavily fractured and Thai burners have combated the cracking by healing the cracks with a flux such as borax. Heating the stones with borax and other chemicals actually melts their surfaces, including the surfaces of cracks. The corundum within this molten material then redeposits on the fracture surfaces, filling and healing the fractures shut. Undigested material cools into pockets of flux glass. Essentially this amounts to a microscopic deposition of synthetic ruby to heal the cracks closed.
In the broadest sense, this is akin to the oiling of emerald – both treatments involve reduction of reflections from included cracks/fissures. Similar to placing an ice cube in water, a filled fracture is much less visible because the filler replaces air (RI = 1.00) with a substance which has an RI that more closely matches the gem itself (1.76–1.77). However, the flux healing of Möng Hsu rubies differs in three important respects:
Hence we have a superior treatment for Möng Hsu ruby, one which is actually more stable than ordinary oiling. So what is all the fuss about? First, purchasers of ruby are not accustomed to buying heavily-fractured stones. Unlike emerald, clean rubies do exist. Second, the process can also be accomplished with heat alone. If such stones are deemed acceptable without further comment, what happens when only heat is used? What is important here is not the how, but the fact that these stones once had open fractures that are no longer there.
But the biggest problem is something quite simple – when Thai burners first started this type of fracture healing, they did not tell their customers. Customers believed they were buying stones to which only ordinary heat had been applied. When they learned otherwise, they rejected the goods.
To most dealers and jewelers, fracture healing with a foreign substance such as flux represents open-heart surgery, not just a haircut. Whether we like it or not, many dealers, jewelers and retail buyers of precious stones do not want to buy stones which have been radically altered in such a way. The idea of flux healing turns them off.
Unfortunately, monkeying with stones and not telling the buyer has been business-as-usual in Thailand for years. It started with ordinary heating of corundums (mid-1970s), passed on to glass-filling of surface pits in ruby (1984), surface diffusion of blue sapphire (1988) and now flux fracture-healing (1992).
Market acceptance of ordinary heating was de facto; with no gem lab in Bangkok in the mid-1970s to warn them, foreign buyers generally found out about this difficult-to-identify enhancement only after their inventory was full of heated gems. This was not the case with the other enhancements. A gem-testing lab was founded in Bangkok in 1978. When the glass pit-filling and surface diffusion first appeared in Thailand, these treatments were quickly recognized by Bangkok gemologists and rejected by the global market as a whole.
But the fracture-healing of Möng Hsu rubies was initially passed over by local gemologists, in part because it is difficult to detect and in part because, frankly, certain Bangkok gemologists became overly influenced by traders. Even when they did detect the enhancement, they downplayed its significance, going so far as to declare that it would not be mentioned on identification reports if it wasn't visible under greater than 10x magnification (ICA Gazette, 1994).* Foreign gemologists and dealers were not so kind. Many rejected such flux-healed goods outright, particularly in the important Japanese market.
This has created a very real problem, where the enhancement is generally accepted by Thailand-based dealers/gemologists, but rejected by those outside the country. The result is that goods are returned amidst much name-calling and hand-wringing, a situation from which only lawyers will benefit. Compounding the problem is the fact that laboratories around the world do not have uniform methods of describing or dealing with this enhancement. Some cannot even properly identify it or distinguish between naturally-occurring inclusions and the flux healing.
Desperately seeking solutions
So, what to do? First, the gem trade must get together to discuss the problem and explore potential solutions. Today's world is one market, not one-hundred. The global nature of the trade makes it important that solutions also be global, not local.
Then, Thailand's gem traders and treaters need to acknowledge that a mistake was made in not declaring this treatment from the outset. In the strictest sense, the problem is one of the Thai gem trade's own making. Had they been honest in properly labeling their goods from the start, they would not find themselves in this position.
On the other hand, foreign buyers need to acknowledge that some sort of enhancement is needed for Möng Hsu ruby. As anyone who as ever viewed the untreated stone can testify, the Möng Hsu ruby is not a viable gem without enhancement. The enhancement results in a material which is both beautiful and stable. There is certainly nothing wrong with that, so long as it is properly described.
Overall, we all must stop kidding ourselves. We must realize that, in the eyes of the retail gem customer, the high-temperature heating and flux healing/impregnation of a ruby is not the same as simply cutting and polishing it. No amount of explaining will make it so. A gem which only requires polishing to reveal its beauty is far rarer than something which needs both polishing and ordinary heating. And that is rarer than something like the Möng Hsu ruby, which needs polishing, high-temperature heating and flux-fracture healing. The market should reflect these realities in its descriptions of goods and, most importantly, in its pricing. Remember, gems and jewelry are luxuries. They compete against a number of different goods and services. If we don't start getting our act together, that retail customer will stop buying more than just Möng Hsu rubies.
Many gemologists state that the quantity of flux glass found in most specimens is evidence that this infilling is deliberate. But there are many traders who claim such fillings result as an accidental byproduct of the common practice of adding borax (sodium borate) during burning.
To put this matter to rest, in September, 1996, one of the authors (RWH) put the question of borax (flux)-based heat treatment to one of Chanthaburi's best-known burners. This gentleman chuckled at the thought of this being an accident. "Of course we do it on purpose," he said. "Most Möng Hsu ruby is not suitable for faceting without such treatment. We must use borax."
Solutions rarely come easily. But the first step to solving any problem is to discuss it. The authors believe it is far better to discuss problems without solving them that to solve problems without discussion. We are interested in the views and ideas of others. Feel free to contact us.
*We refuse to even comment on that silliness.
Written in the summer of 1997, this article appeared in the Australian Gemmologist (1998, Vol. 20, No. 2, pp. 70–74). It also suffers from the all-too common distinction of being rejected by another magazine for being "too controversial" – in this case, the ICA Gazette. I revised it slightly in Jan.–Feb., 2002, mainly to remove the term glass filling, for according to my current knowledge, the process is mainly one of fracture healing rather than fracture filling.
A Reader's Response
Gemologist Adolf Peretti makes the following comment…
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