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Demantoid Garnet

Written by rdjadmin On May 2, 2013.

Twenty-eight years after it was discovered in 1868, gemology pioneer Max Bauer wrote that demantoid garnet would probably never earn full-fledged gem status. Much as he admired the stone, Bauer thought it was too small, soft, and scarce to merit anything more than curiosity.

Just about the same time, the late nineteenth century’s other great gemology pioneer, George Kunz, was in the Ural Mountains of Russia, demantoid’s prime source, buying every piece of demantoid rough he could find. Kunz, on leave from Tiffany’s where he served as the store’s chief gem buyer, was financed by banker/tycoon J. Pierpont Morgan, an avid gem collector.

For more than a decade, Kunz had been a devotee of the Russian green garnet, so much so that Tiffany’s made more extensive use of the gem than any other jewelry store of the age. Indeed, demantoid was as closely associated with Tiffany’s in the late nineteenth century as tsavorite, a distant-relative green grossular garnet discovered 100 years after demantoid in East Africa, is with Tiffany’s in the late twentieth century. True, demantoid was a darling of upper crust English and French jewelers, as well as Faberge. But the gem owes much of its popularity with connoisseurs today to the Tiffany mystique: despite the fact that it has been at least 65 years since the last significant production of Ural Mountain demantoid.

Thanks to Kunz, demantoid achieved, and still retains, an importance far disproportionate to its availability. “Maybe one in every 10,000 pieces of Victorian jewelry used demantoid,” says jewelry historian Joseph Gill. “Yet you’d never think how little of it there actually was with all the fuss they make about it today.”
Why the big fuss? The gem’s name gives a clue to the cognoscenti’s lingering love.

Dispersion Greater Than Diamond

Almost all garnets are plagued by very low dispersion, the separation of light into spectral colors as each wavelength bends different degrees. But demantoid, a member of the andradite family, is an exception, blessed with more of this attribute than even diamond, a stone prized for its dispersion. No wonder, then, that the garnet’s first sellers named it demantoid (meaning diamond-like), after the Dutch word “demant” for diamond. (In case you’re wondering why marketers used a Dutch word, keep in mind that Amsterdam was still the world’s principal diamond-cutting center at the time the garnet first came on the market.)

The new garnet’s fiery brilliance gave the stone, usually found in small sizes, a decided edge over emerald and peridot, the period’s leading green gems. Indeed, Gill says, demantoid was often sold as “olivene” or “Uralian emerald.” That is why many pieces of Victorian gemstone jewelry made between 1885 and 1915 feature demantoid. In fact, the stone is almost wholly identified with the Victorian era.

Luckily for demantoid, America and England had fallen under the heavy spell of Darwin-inspired naturalism. The resulting fascination with brute nature was manifested in jewelry design as a voguish use of bird, fish, flower and reptile motifs. Since green symbolized nature, jewelers gravitated toward emerald. However, motif pieces were set with many small stones and in small sizes, nothing could match the brilliance of demantoid, so most of the pieces were set with these gems.

No doubt, larger demantoids would have figured as prominently in late nineteenth century jewelry, only supply prevented it. The stone is extremely rare in sizes over two carats.

The Telltale Inclusion

Demantoid garnet is probably the only gem whose inclusions are considered an aesthetic property, as important as color and brilliance. Believe it or not, the value of a stone depends heavily on the prominence and definition of what are called “horse-tail” inclusions (bundles of byssolite- a form of asbestos- that spray out in a curve from a central chromite crystal).

Although a few yellowish-green garnets containing horse tails have been found in the Italian Alps, this happens so infrequently that most gem dealers still consider the horse tail to be, in effect, a Ural Mountain birthmark. “Technically speaking, the horse tail isn’t conclusive proof of Russian origin,” warns one gemologist. “It’s just a very good indicator. To be absolutely sure, you’d have to do chemical analyses.”

Consumers may wonder why such ado is made over finding one particular type of inclusion in the first place. Does it really matter if a demantoid is from Russia? The answer is yes. A large part of demantoid’s mystique, historians note, is its Ural heritage. Since these mountains also produced small amounts of alexandrite, emerald and pink topaz, the best of which are said to be paragons of these species, Ural mountain gems have a prestige based on locality.

This doesn’t mean that a horse-tail is all that matters when buying demantoid. But its presence certainly helps to distinguish stones from horse-tail-free ones found in Czechoslovakia, Arizona, Mexico, and, more recently, Namibia, as well as the majority of stones from Italy. Another difference is color. Most non-Russian stones are so yellow (the result of coloring by iron as opposed to chromium) that they should perhaps be called topazolite, a greenish-yellow andradite.

Record Sale

Of the 325 items offered at Christie’s Hong Kong $12 million jewelry sale on April 28, Lot 1261 was hardly the most valuable. But this belle epoque ring featuring a 4-carat oval-cut demantoid garnet surrounded by old-mine and rose-cut melee diamonds was among the rarest, the most unusual, and the most soul-stirring-enough to drive the final price for the piece $8,000 over its highest pre-sale estimate to $40,000. While that’s nowhere near the kind of cash routinely forked over for kindred-quality specimens of their most favorite green gems, emerald and jadeite, it’s startlingly big bucks for green garnet. How do you explain that kind of money being spent for an andradite when ordinarily $4,000 per carat is considered top dollar for this species?


Written by rdjadmin On May 2, 2013.

It’s white and bright, clean and clear-all the attributes you associate with diamond. Yet no one would mistake it for the king of gems. Hey, you want a natural gem that people would swear is diamond, try white sapphire or colorless topaz. So, then, why write about danburite?

Designer Sharon Curtiss at The Gem Vault in Flemington, New Jersey, can give you lots of reasons. And since she recently won first place in the Jewelers of America’s annual design competition, and uses danburite as frequently as any jewelry artisan in the world, it can’t hurt to hear her out. To begin with, she insists, “White doesn’t have to mean diamond. I can do things with danburite I would not do with diamond or a gem I think of as a diamond substitute.”

Like what? I pester. “Like this,” she answers, and then shows me a pair of knockout earrings, each featuring a danburite weighing around 2-3/4th carats set in 14k white gold and discreetly studded with melee diamonds. The woman who bought them told Curtiss she knew the feature stones weren’t diamonds, but was fascinated by their non-diamond look-then won over by their non-diamond price: $899. “There was no way the customer could buy two decent diamonds with a total weight of 5 carats for the price of this piece,” Curtiss says. “Affordability became a big incentive to fall in love with the earrings.”

All of which brings Curtiss to the next, and possibly main, reason for using this calcium boron silicate as often as she does. “Danburite gives me the chance to create a big, white, classic look-elegance that can be worn with anything,” she says.

And she can do so for under $20 per carat-one tenth the current rising cost of increasingly scarce white sapphire. Of course, with a hardness of 7, as opposed to sapphire’s Moh’s scale rating of 9, danburite probably shouldn’t be equal in value to corundum. After all, a 7 rating for danburite sends hands-off signals for ring use-or, at least, everyday ring use. Aware of the gem’s borderline suitability for rings, The Gem Vault’s designers restrict danburite mostly to earrings or pendants. But white on the ear or on the neck is just as noticeable and nice as white on a finger.

Nevertheless, if price is a determining factor in the choice of danburite, why not use better-known and less expensive white topaz, I ask Curtiss. “I don’t want to get mixed up with topaz at the moment,” she says, alluding to the widespread use of irradiated and coated topaz. “Danburite is untreated and it is rare-two wonderful strengths on which to build a reputation.”

By now, you may want to know more about this obscure but jewelry-worthy gem named after its place of first encounter in the 19th century near the southern Connecticut town of Danbury. Read on.


As you can guess, there isn’t a large literature on danburite. This may be one of the few trade press articles to ever promote this gem. Modern Jeweler began its advocacy of danburite in a May 2006 survey of designer discovery candidates called “The Six Best Gems You Never Heard Of.” Although the other stones featured in that overview made it to the mainstream, danburite remains an unknown.

Even segments on shop-at-home TV have failed to improve the gem’s prospects for popularity. Usually, on-air exposure starts a chain reaction of demand. That hasn’t happened with danburite. No one is sure why. One dealer who sells it thinks the trouble may be “its total lack of dispersion.” Fire, he reasons, would give it telegenic gleams of spectral color that might excite jaded viewers and entice couch connoisseurs. Curtiss acknowledges this drawback but says danburite makes a good first in-store-if not on-screen-impression because of its very satisfactory brilliance. Of course, stones must be well-cut to possess this virtue.

Today, all colorless danburite comes from Mexico. Sizes range up to 10 carats, although some behemoths make it to market. No dealer we talked to has seen, let alone sold, any New England danburite. So there is no way I can describe the difference in appearance, if any, between the two varieties.

Curtiss and Gem Vault’s danburite supplier Dudley Blauwet, a dealer based in Louisville, Colorado, laud Mexican material for a very faint tinge of pink they find preferable to the hints of cape yellow or champagne brown seen in many diamonds. However, both suspect this vaporous pink disappears gradually after exposure to light.

Should danburite ever catch on, it is worth noting that it does come in colors. Of these, Madagascar produces the best I have seen, stones which at their best sport medium root beer and light rust browns that are glorious. How much or little of these fine colors are presently coming from this African gem cornucopia is hard to say. Even among African stone specialists, danburite is not currently on many to-buy lists.

Up until a decade ago, dealers who specialize in collector gems often saw earth-toned varieties of this gem in a golden-yellow to orangey-brown color range from Burma. Since brown family colors were not then appreciated, there was no reason to continue mining at-or, at least, importing from-this source. Consequently, laments one of Blauwet’s associates, “I haven’t seen those colors for at least ten years.” But who knows? As word spreads about danburite, maybe more of the species’ sepia splendors will start reappearing.


Written by rdjadmin On May 2, 2013.

The natural pearl isn’t the only worldwide casualty of pollution in the planet’s seas. Now coral, the other great organic sea-gem, is in big trouble too — at least in its finest, most coveted red colors.

Highly treasured in ancient India, Persia and Rome, coral is nearly as much a mainstay of gemstone artisanry as amber and ivory, especially with Native American craftsmen. As with other organic gems, coral was widely believed to have medicinal and mystical powers. Even today, coral powder is a popular aphrodisiac in India, which use prompts some gatherers to dynamite coral reefs. Such tactics, of course, only aggravate the fine-goods supply problem. But coral must fend off graver threats than TNT.

As a living organism, coral faces a slew of challenges to its survival, especially as the waters in which it lives become progressively contaminated. The creation process of the gem coral is peculiar and complicated. But, simply put, here’s how it works: A multi-cellular animal called the coral polyp bands together in colonies with millions of its fellow polyps. For protection, each secretes a protective jacket for itself of pure calcium carbonate into which it retreats when threatened or not feeding. As the colony builds these shells, they couple together into branches and, if large enough, reefs.

Unfortunately, these calcium carbonate structures — which Gemological Institute of America chief gemologist John Koivula calls “condominium complexes”– cannot withstand merciless predators such as the Crown of Thorns starfish which attach themselves to the colony and suck out all the lives. Often the polyps will abandon their homes when water conditions change for the worse. Whether ravaged or deserted, it is these coral skeletons (Koivula calls them “abandoned housing projects”) that coral fishers process into beads, cabs and carvings.

Because coral is pure calcium carbonate, it is sensitive to chemicals, detergents, perfumes, even body acids which can eat away at it. That’s why dealers and gemologists recommend periodic cleaning of coral in a mild soapy solution to rid it of all these abrasives. Even so, some softer corals, such as those from the Mediterranean, may need re-polishing every few years or so.

Red Sales In The Sunset

Luckily, some corals are more resistant to chemicals and acids. The toughest, according to a Los Angeles coral specialist, come from the Sea of Japan, which is also the prime source of true ox-blood coral. “The Mediterranean produces red coral, too,” he adds, “but it is not as hard as the material from Japanese waters.”

In recent years, Taiwanese coral fishers have replaced the Italians, famous for centuries as coral carvers and cutters, as the main harvesters of this gem off Japan. But lately the Japanese fish and wildlife authorities have been enforcing strict coral quotas in the Sea of Japan and, as a result, sharply curtailing fishing activity in these waters.

That leaves the Mediterranean which, long before the Japanese reined in on coral fishing, was so fished and polluted that it was well on its way to becoming a lost cause for red coral. Not surprisingly, supplies of ox-blood and deep-red coral are dwindling sharply, despite exploration of farther depths for coral colonies.

As dealer inventories of ox-blood and dark-red material disappear, prices for these most-prized of coral colors soar. Consumers may have to pay a few thousand dollars today for a very fine 18-inch strand of 8-9mm ox-blood beads.

Deep red is not the only coral hue that appeals to connoisseurs. Many prefer the far-lighter blush-pink shades of coral, commonly called “angel skin.” Prices for this lovely material are slightly less than those of ox-blood.

It goes without saying that the high cost of true red coral has invited rampant treatment of this gem. Colorless to near-colorless material can be dyed a reddish shade, one which dealers say is immediately distinguishable from natural-color coral. Some processors are taking shivers and shavings of coral branches, combining them with a chemical binding agent, and selling the final reconstituted product as genuine coral.

So far, reconstituted coral is not as rampant as, say, reconstituted turquoise. But, some importers fear, it could become so if prices for red coral keep climbing. “I have no objection to “pressed coral”, or whatever you want to call it,” says one, “but I just wish it would be sold as what it is — and not what it isn’t.”

Color-Change Spinel

Written by rdjadmin On May 2, 2013.

If ever there was a song that summed up the plight and potential of spinel, it’s one written by Irving Berlin for the show “Annie Get Your Gun.” Its title and opening line go like this: “Anything you can do, I can do better.” The “you” in this case would be corundum and the “I” spinel.

Face it, spinel has been living in the shadow of sapphire and ruby for the entire stretch of living memory. So it is with slight trepidation that I report on still another member of this family that so expertly mimics corundum you are likely to confuse the two.

I’m talking about color-change spinel, found in Tanzania, Sri Lanka, and Madagascar and solidly entrenched since its discovery in those places as a collector’s stone. Such elitist status explains why many collectors treat their knowledge of this stone as privileged information. Indeed, two gem collectors I talked to wanted me to drop plans for this “Gem Profile” and keep the gem’s existence secret. “What good is it going to do,” asked one, “for you to blab about color-change spinel to the industry at large? There isn’t enough material to meet collector demand.”

His resistance is understandable. Wider awareness of color-change spinel can only decrease already sparse supplies and increase stubbornly low prices. It is one of the chronic contradictions of the spinel market that prices for most stones are a fraction of those of the rubies and sapphires they so closely resemble. I say “most” because prices for top-grade recent-find red and pink spinel from Tanzania and Vietnam (as well as grandiose goods from Burma, that old standby for spinel) have joined those of their fine ruby and pink sapphire brethren in the Himalayan heights of precious stone value.

But prices for class A color-change spinel are far more down to earth-if not a little below sea level. Raja Shah of Color First, Tampa, Florida, who supplied us with a generous sampling of color-change gems, doubts the 2.01 carat spinel used as an exemplar stone for this “Gem Profile,” could command more than $500 per carat at retail.

Not that it’s for sale. It isn’t. This stone and a .77-point beauty sent by Simon Watt of Mayer & Watt, Maysville, Kentucky, sit securely in their owners’ private collections awaiting the find of comparable-quality companions. As Shah puts it, “Current prices for color-change spinel are an insult to their beauty and rarity.”

Now you can understand why collectors want me to stay away from this subject. “If ever a gem was a limited edition, it’s got to be color-change spinel. Yet it is scandalously affordable,” one said. “I’d hate to think other collectors waiting for the chance to own one would be outbid by somebody looking for an investment rather than a thing of beauty.” I told him this will happen whether or not I write my story. Here’s why.


When it comes to color-change gems, there are few choices to be made. Best-known and most popular by far among these phenomenon stones is alexandrite-a green-to-red chrysoberyl with a hardness of 8.5 that is found in Russia, Sri Lanka, and Brazil. Prices for the best stones are generally five and six figures.

Next in supply and stature among the slim ranks of color-change gems is blue to purple sapphire, which caught on with both collectors and designers after discoveries of deposits in Tanzania in the 1960s and Sri Lanka even earlier.

Third, but a viable candidate to leapfrog over sapphire in status, comes color-change garnet. A recent find in Kenya has given the world its first true-blue garnet-admittedly only in fluorescent light. But when it comes to garnet, half a blue is better than none.

Fourth in the color-change rankings-both in production and prestige-is spinel. Granted, sizes tend to be less than 1 carat, but its hardness, which is 8, is a plus. Nevertheless, the real appeal is aesthetic.

For me, spinel has a distinctive color change that only superficially resembles that of color-change sapphire. It flips from a steely Hope Diamond blue to a subtle violetish-purple that bears a strong resemblance to some of the rarest and most dramatic of all monochrome spinel hues-in this case, blues from Sri Lanka and lavenders from Vietnam.

Given the patience-straining availability of both blue and violet in normal spinel, the case for ownership of the frustratingly few specimens of the color-change variety is as potent as any that can be made for a color-change gem. At the risk of further aggravating the collectors we talked to, it seems irresponsible not to state the plain truth about color-change spinel: It is a true treasure and a true bargain. This fact begs another truth: The days of under-pricing this two-toned gem are about to end.

Color-Change Diaspore

Written by rdjadmin On May 2, 2013.

Before it was Zultanite, before master lapidaries like Steven Avery cut it, and before no more than a few stray souls saw any reason for excitement about it, Turkish diaspore caught jewelry artisan Diana Stern’s roving eye at the Tucson gem show and she paid $200 per carat for a 3 carat stone. “It was one of the few good stones they had,” she recalls of the purchase more than a decade ago, “and I knew it was preposterously overpriced. But you know the old story about finding something new that no one else has and wanting to be the first person to own one.”

When Stern first saw the stone, she was impressed by what she describes as its “dusty pink champagne color studded with flecks of scintillation.” Not yet realizing it was a color-change stone, she insists she would have bought it even if it only exhibited one color state. “Remember, this was before we had stones around like sphene that display all those big flashes of color,” Stern says. “I took to the gem’s fireworks.”

Nevertheless, once she saw the gem’s light cypress-green in sunlight, she began to think of it as “Turkish alexandrite,” which is what she likened it to when she sold it mounted in a ring at a crafts fair. “I hated to part with that stone, but I reassured myself I would be able to find another as good.”

A dozen or so years later, at the 2006 Tucson show, she finally did. “I thought I had caught the first wave of supply,” she says with a laugh. “Little did I know I wouldn’t see the second wave for at least a decade.”

Stern was the only person I ever met for whom Turkish diaspore kept the lavish promises made for it when first introduced into America in the mid-1990s. Hailed as a major new phenomenon gem, this magazine devoted a “Gem Profile” to the material, but the article was based on hype and hope. Somehow I was talked into believing this gem would earn the praise its first promoters heaped on it.

Apparently, Stern and myself weren’t the only ones who bought into diaspore’s bright future. Murat Akgun sank much more than $100,000 of his own money into the venture-and had no other way to recoup his investment than by turning his faith in the gem into fact. To do so meant finding new partners and throwing even more money into his dream. Now that dream is beginning to pay off.


Diaspore is a relatively new gem, first faceted in the 1970s-and then mainly as a curiosity. The highest grade deposit known is found 4,000 feet up in the mountainous remotes of Anatolia, Turkey, miles away from the nearest village. When Akgun first became involved with diaspore, he believed his partners owned the mine. They didn’t. And it has taken him years to obtain a lease of his own.

In the meantime, locals were poaching material and selling it in poorly-cut form that did nothing to improve its reputation or prospects. Akgun admits there is a still a backlog of these inferior goods on the market and that it makes his job all the harder.

But starting in 2005, he began to sell superbly crafted diaspore under the new brand name of Zultanite, which is a vaguely Turkish-sounding reference to the sultans who founded the Ottoman Empire. Akgun formed a company Zultanite Gems LLC, based in Fort Lauderdale, Florida, and entrusted the cutting of his best stones to top-notch lapidaries who were not intimidated by its perfect cleavage and able to orient stones to maximize color change and sparkle. Of course, this meant huge sacrifices of rough, but the final beauty more than made up for loss of bulk.

With a hardness of 6-1/2 to 7, diaspore doesn’t present any more problems for wearers than, say, tanzanite-another gem known for shifts of color in different lights. Although Akgun characterizes diaspore’s color change as going from kiwi-green in sunlight to rhodolite pink under incandescent light, this writer has seen lots of intermediate shades that range from what might be called dusty avocado and sage-green to light pinkish terra cotta and soft flax-brown. Both green/olive and pink/brown color states fit right in with popular earth-tone color schemes.

Having attracted justified publicity for Zultanite, Akgun is focused on making a market for his brand. Akgun sees the stone as a designer gem-perfectly suited for one-of-a-kind pieces of jewelry. But at this year’s Tucson show, the most interest was paid by buyers from shop-at-home TV networks on the constant prowl for new products. Some even took large samples of goods back to headquarters for evaluation.

If Zultanite becomes home-shopping air ware, will that be good for its image as a designer gem? And even if Akgun can develop dual mass and collectors markets for diaspore, can what is still a small, primitive pick-and-shovel mining operation back in Turkey support two tiers?

A year ago, when Akgun had a more modest inventory, the answer would have been no. But now that mining is getting organized, he believes he can satisfy such demand. Let’s hope so now that the trade press is paying generous attention to Zultanite. For sure, the company’s booth was a must-see attraction at this year’s Tucson show. Says Stern, who keeps a scrapbook of the friendly write-ups the gem is getting: “I want to say, ‘See, didn’t I tell you so?'”

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