Jewelers who planned to stock fine blue-color moonstones in the near future might have to delay their plans indefinitely now that the world’s main vein for this gem in Sri Lanka has run bone dry. What remains in the way of this feldspar are mostly run-of-the-mill stones that resemble water with milk of magnesia stirred in. For an idea of what used to be, turn your eyes to the facing page. There you will find pictured the maybe-extinct variety of this gem that many Europeans, principally Germans, found lovely enough to frequently encircle with diamonds.
Why so few U.S. jewelers ever knew such moonstones existed is a mystery. But those few in the know call them “blue-sheen” stones, the name they go by in Europe. Such moonstones are invariably crystal clear with a floating blue to blue-white opalescence on their surface.
A decade ago, when larger blue-sheen moonstones were very plentiful, jewelers could buy them for under $10 per carat. Nowadays the price of such stones can easily be $50 per carat for sizes over 5 carats and can just as easily top $80 per carat for sizes over 10 carats. As shocking as such prices seem to old-timers, they are fair, especially since the sole source for blue-sheens, Meetiyagoda in Sri Lanka, ceased production in 1987. “All most dealers have left are tiny little stones, nothing of any consequence,” says gemologist Charlotte Crosby, a buyer for bead stone specialist Lucien L. Stern, New York. “So it looks like those who want the blue-sheen material in decent sizes are going to have to depend on antique and estate pieces from now on.”
Instead of Pearls
The bad news about good moonstone puts jewelers who sell this gem principally as a birthstone in a bit of a quandary. A birthstone for June, moonstone is usually considered an alternate to pearl. However, some birthstone lists published in Europe actually place moonstone ahead of pearl. Is this merely an alphabetical courtesy? Or is it a sign of special preference?
It’s probably the latter. One of the earliest and best sources of moonstone was St. Gotthard in Switzerland, formerly known as Mount Adular, from which is derived the root of moonstone’s old name, adulaira. Although that name is rarely used today, it is still universal to refer to moonstone’s sheen as adularescence. In actuality, opalescence, this sheen results from the interplay of light with layers of tiny albite crystals in these stones. The thinner the layer, the bluer the sheen; the thicker, the whiter.
In short, moonstone’s mainstay status in German-speaking Europe stems from pride in its once local origins. When choosing moonstones, European connoisseurs look for two things: ideal body and sheen color. What’s the ideal? For body color, it’s completely colorless transparency; for sheen, it’s a deep, haunting sky blue which glides across the dome or table of a stone as it is moved against the light. Like most ideals, the one for moonstone is rarely attained. Los Angeles-based moonstone expert Michael Schramm, Sapphires Unlimited, estimates that, at most, one out of every 100 Sri Lankan moonstones ever qualified as “blue.” What are known as “semi-blue” and “silver-white” stones were sometimes passed off as blue sheen. Years ago, when Burma was a big producer of blue-sheen goods, there was no need to stretch this term so far out of bounds. But, based on reports from dealers who travel regularly to Thailand, where most new Burma gem production is smuggled to market, Burma can no longer be counted on for any more than an intermittent handful of blue beauties. Although America and Mexico, among others, produce moonstone also, output is sparse and far from ideal.
This leaves jewelers who wish to stick with moonstone little choice but to make do with lesser grades. Don’t get us wrong. Some of the skim-milk blues to sage-beard whites are very lovely. Moreover, with their soft, lustrous appearance, it is easy to understand why birthstone list compilers assigned moonstone an understudy role for pearl. Their cost, usually under $20 per carat for 10- to 20-carat sizes, is certainly a consoling factor. What’s more, prices drop very sharply for stones whose body color becomes increasingly brownish or which show the tiny stress marks that are a characteristic of this stone. Or one can desert blue sheen entirely in favor of special effect moonstones and even fellow feldspars.
Stars, Eyes and Rainbows
Many highly cloudy moonstones, some with strong body color, are cut into high-domed cabochons so that their sheen collects in a chatoyant silver-white band across the top. These stones are known as “cat’s-eye moonstones” and are readily available in 10- to 20-carat sizes for under $30 per carat. Small stones can be bought for under $10 per carat.
Occasionally, cat’s-eye moonstones have a second band, or ray, intersecting the first at a right angle. Some dealers call these stones with cross-shaped eyes “star moonstones. Prices for these stones are impossible to quote since the dealers we talked to for this story had none in stock.
Retailers who seek stones more reminiscent of conventional moonstone may be interested in a new-variety feldspar, properly called bytownite, coming out of India. These stones are called ‘rainbow moonstones’ because they feature a multicolored adularescence. The finest have a red. dish-orange or sometimes a lavender sheen with areas of green and blue. Lesser grades have a more brownish sheen.
After only a few years on the market, the very finest rainbow moonstones in scarce 10-carat sizes already command $100 per carat at wholesale-and prices could very well be heading higher. Moonstone specialist Manu Nichani of Temple Trading Co., Encinitas, Calif., says fierce German buying of this gem at often heady prices has crowded out more faint-hearted American buyers unable to accept prices for a new-entry feldspar that have outdistanced those for blue- sheen moonstone in no time at all.
Rather than face high prices, however, some American dealers blame their difficulties finding the new rainbow moonstone on supply when, in reality, the situation stems more from demand. Goods are bypassing the U.S. market because of voracious foreign consumption at what are untenable prices in the U.S. importer market.
Meanwhile, a few last pointers when buying moonstone conventional or otherwise. Jewelers new to this gem should bear in mind that moonstones have a far-from-rugged hardness of 6-6 ½ on the Mohs scale. Often they also have strong cleavages. The bottom line: tell customers to wear these gems with care.
Please note: this profile was originally published in 1988 in Modern Jeweler’s ‘Gem Profiles: The First 60’, written by David Federman with photographs by Tino Hammid.
The 9.52-carat moonstone shown in the header image is courtesy of Michael Schramm, Sapphires Unlimited, Los Angeles.