Thai ruby still has plenty of detractors in the world gem community. To many old guard dealers, it is a poor substitute for the Burmese variety of this corundum, despite the fact that, once a common substitute for Burmese goods, it is now more rare than corumndum from its high-status neighbor.
In addition, Thai rubies come in larger sizes and are generally cleaner and brighter than Burmese stones. Nevertheless, because connoisseurs found them so unforgivably purplish, so unbearably reminiscent of garnet, Thai rubies have never received much respect. Even when they have a pure red color, black reflections known as extinction can reduce the overall impact of their color.
Thai dealers were not insensitive to the establishmentís lack of esteem for their rubies. But to change its harsh, unaccommodating attitude meant finding the means to change the color of their stones. Some time in the mid- to late-1970s, the Thais discovered a method, using high heat kilns, and, later, controlled-atmosphere furnaces, that eliminated purple and left their rubies a far more desirable red.
In this way, modern color alchemy broke down longstanding resistance to Thai ruby.
But the triumph was short-lived. Ironically, after Thai ruby earned the lionís share of the market in the seventies and eighties thanks to heating, in the nineties Thai treaters learned how to enhance ruby from a new deposit in Burma known as Mong Hsu. The prolific new mine which offered typical Burma color at an affordable price came on to the market as supplies of Thai ruby were lagging. Thai deposits, some depleted and some just too expensive to compete with the affordable material now available from Burma, have been rendered irrelevant again.
Because Thai ruby and Burmese ruby when side by side are quite different, manufacturers generally choose all one or the other. The tide turned quickly from Thailand to Burma as a result.
Although few connoisseurs would argue that the best ruby from Thailand surpasses the best ruby from Burma, Thai ruby does have many advantages in medium qualities. Thai rubies can be remarkably clean and lively. Burma ruby often has a hazy, cloudy quality that softens its appearance and makes it less brilliant. Thai ruby often can be cut in spectacular fancy shapes, including marquise shapes and emerald cuts that are difficult to find in Burmese material.
While Burma ruby can become pink in tone, Thai ruby is resolutely red. It has a consistent depth of color and a crispness that some prefer. And now it has rarity as an advantage as well.