Just a few years ago the presence of numerous Thai rough buyers in Sri Lanka’s sapphire fields was cause for jitters among that country’s gem dealers. At the same time, their presence at Australia’s and Nigeria’s sapphire areas was cause for joy among miners there. After all, nobody bought anywhere near as much rough sapphire or paid higher prices for it than the Thais. They could afford to outbid all others because they knew how to treat heat what they bought to coax the best color out of it.
Today the army of Thai rough buyers stationed in Sri Lanka, Australia and Nigeria is a skeleton force. Where has it gone? Back home. There, blue sapphire is the most plentiful ever—nearly all of it coming from a cluster of hyperactive mines some 60 miles to the west of Bangkok in Kanchanaburi province. “Why buy sapphire in someone else’s backyard when you can dig it in your own?” asks Michael Avram, Maverick Industries, New York.
But this isn’t the normal pick-and-shovel digging one sees elsewhere in Asia and Africa. This is mechanized mining using heavy earth-moving equipment and automated rough extraction plants. “You almost feel like you’re at a diamond mine,” says Robert Kammeling of the Gemological Institute of America, a visitor last year to the largest of the new sapphire ventures, S.A.P. Mining Co. Ltd., which reports Jewel Siam, recently applied for a listing on Thailand’s Stock Exchange.
Until 1987, mechanized mining was verboten in sapphire-rich Kanchanaburi, although a fact of life in ruby-rich Chantaburi. After years of stubbornly resisting the use of heavy machinery for mining, Kanchanaburi’s local government decided to relax long-standing restrictions against it.
By the beginning of 1989, 50 or so mechanized mining ventures had been given a go-ahead at various sites around Bo Phloi. The next year, when these operations came on stream, buyers in Bangkok noticed a deluge of sapphires. “Although I had been seeing Thai goods since around 1985, it wasn’t until 1990 that the avalanche from Kanchanaburi hit the market,” says Benny Hakimi, Intercolor, New York.
Since then, all but three or four of these new mines have been shut down—not because they ran dry but because they ran in the red. Even so, huge backlogs from old and massive output from remaining operations keep Thailand the world’s largest corundum producer, responsible for as much as 75% of all the blue sapphire currently being offered for sale in Bangkok.
The Home Advantage
Long used to dominance in ruby mining, Thailand was never No. 1 for blue sapphire production before 1990, although its huge deposits have been known about for 80 years. Only two years ago, the top-ranked source for blue sapphire was Australia. In fact, when its production peaked a decade ago, Australia supplied 65% to 70% of the world’s sapphire rough, says Brisbane, Australia-based gem mining expert Grahame Brown. Just before the floodgates opened at Kanchanaburi it was 50%. Now Brown puts Australia’s “rapidly diminishing” market share at 20%, perhaps less.
“Although Australia’s decline can be partly blamed on shrinking sapphire reserves, the real culprit is a shrinking customer base. The Thais, who bought nearly all of Australia’s sapphire, cut back foreign purchases drastically once full-scale mechanized mining started at home.
While Thai sapphire enjoys a distinct home advantage, it has more going for it than local pride and plenitude. It’s got far better color than either Australian or African material, most of which is simply too dark. “Kanchanaburi goods have a much purer blue, with far less extinction [areas of blackness],” says Hakimi. Although many stones from Kanchanaburi are overdark, there are enough with medium tones and their open or royal blue color to satisfy voracious demand from Thai jewelry makers and U.S. and European gem dealers. “Only the Japanese have yet to be won over in a big way to Thai sapphire,” says Hakimi.
Sticklers for brilliant, high-clarity goods, the Japanese buy only the relatively few Kanchanaburi stones, mostly in 1- to 2-carat sizes, that are silk-free or close to it. For this reason, they remain the biggest buyers of Sri Lankan sapphire in the world. Ironically, Sri Lankan goods are also, as Avram puts it, “loaded with silk.” But for reasons not yet known, silk in Thai stones cannot be dissolved in ovens without the loss of color, while silk in Sri Lankan stones can. “Heat treatment of Thai sapphire is still in a developmental stage,” says Avram. “But already I’m seeing colors in it I didn’t see two years ago.”
Thai stones compensate for silk with color uniformity usually lacking in their Sri Lankan counterparts. That means little or no color zoning. “In Sri Lankan sapphires, you often see color concentrated near the culet,” Hakimi notes, “making it risky to recut them because of potential color loss.”
Because color is more evenly distributed in Thai stones, it is more common to see them cut without the big bottoms sapphires one sees in many Sri Lankan stones. What’s more, many Thai sapphires cut for bulk, not beauty, are recut from common-place cushion shapes to round and emerald shapes without significant color loss.
For every Thai sapphire that is faceted, at least two are cut as cabochons “to take advantage of their intense, even color,” says Cheryl Kremkow of the International Colored Gemstone Association Gembureau in New York. Most of these cabs are sold to Europe.
Demand for both faceted and cabochon Thai sapphire is now concentrated in sizes from ½ to 5 carats, with U.S. buyers overseas paying around $40 to $60 per carat for parcels of better-grade cabochons and $300 to $700 per carat for large lots of medium-to-better grade faceted stones. Scarce fine stones between 1 and 5 carats that Avram describes as “transparent, free of silk and medium blue” command $400 to $1,000 per carat on the Bangkok market. Overall, Kanchanaburi goods are filling a long-standing supply gap in the middle-quality range between Australia and Nigeria on the lower and Sri Lanka on the upper end.
Given its swift acceptance by gem dealers and jewelry makers alike, it is surprising to learn that Thai sapphire is not yet readily available in popular calibrated sizes. If the short-age continues, it will almost surely cause problems next year because backlogs of fine Australian material are practically exhausted, leaving only commercial grades. Still, Bangkok dealers hesitate to cut calibrated Kanchanaburi stones. “The Thais know if they offer Kanchanaburi goods in calibrated sizes no one will want Australian goods,” Hakimi says.
Please note: this profile was originally published in 1992 in Modern Jeweler’s ‘Gem Profiles/2: The Second 60’, written by David Federman with photographs by Tino Hammid.
The 2.75-carat Thai sapphire shown in the header image is courtesy of Overland Gems Inc., Los Angeles.