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Chrome Diopside

Written by rdjadmin On May 2, 2013.

Until recently, it wasn’t easy being green for any gem except emerald. Things began to change when tsavorite came on the scene in the early 1970s. Thanks to sponsorship by Tiffany’s, this East African green garnet set a second standard for green gems. Being cheaper than emerald certainly helped tsavorite break the color barrier. But lower price alone can’t explain tsavorite’s impact. After all, lots of other green gems like tourmaline and peridot were far cheaper than this garnet.

No, the gem had to boast more of an edge over emerald than price. And it did: better clarity, brilliance and hardness. Plus, color that held its own against all but the finest emerald. Then, when tsavorite started commanding premium prices due to its scarcity, a funny thing happened. Instead of switching back to emerald, the gem trade found for the first time that jewelers wanted, of all things, a tsavorite substitute. At first, look-alike chrome tourmaline filled the bill-before becoming nearly as scarce and expensive as the garnet it was meant to replace.

By now, converts to tsavorite were hooked on the kind of bright, rich color it provided. So they began to clamor for still another green garnet stand-in. Peridot was too yellow. Most other tourmalines were either too light or too dark.

That’s when specialists in esoteric gems began dropping mentions here and there of chrome diopside, a virtual unknown. But these dealers didn’t dare make a big ado over this gem because supplies were too limited to support demand. In addition, most material had a color similar to that of peridot-nothing like the deep green everyone was looking for.

Then, in 1988, rumors of a momentous new find of chrome diopside in Russia started circulating in the trade. Dealers who saw this material when it first surfaced in Europe raved about the resemblance of its color to that of tsavorite and chrome tourmaline and raved as much about its price: only a fraction of these gems. After the wall fell and dealers began exploring the new possibilities for marketing Russian gems, the rush was on. Chrome diopside has been granted class one export status along with diamond and emerald, and alexandrite.

Siberian Green

Chrome diopside is mined in a remote location in Eastern Siberia known as Inagli in the state of Sakha, formerly known as Yakutia. The area is better known for its impressive diamond deposits.

Chrome diopside is part of a large family called “pyroxene.” The diopside branch gets its name from a Greek word, diopsis, meaning “to have a double appearance”-no doubt a reference to its pleochroism, the tendency of certain gems to show different colors when viewed in different crystal directions.

The deep rich green of the Siberian stone is due to chromium, the “chrome” of this gem’s rather inelegant name. You might ask why this pretty green gem has been saddled with a name that soulds like a rust protectant? Because the first market for any gem is gem dealers. And to gem dealers, chrome is a magic word: the gem ingredient that is the source of the most spectacular gem colors. Chromium gives ruby its red, emerald its green, and alexandrite both red and green. Chrome tourmaline is the greenest of tourmaline. To a dealer’s ear, “chrome diopside” means this diopside gem will not only be green, it will be a rich saturated green. A green with impact, the green of money.

In fact, if anything, chrome diopside has too much green. Sizes over three carats steadily darken until they lose life, making chrome diopside with the dream green only available in small sizes.

This limitation keeps prices affordable. One carat stones with a nice green color can be less than $100. Prices for cabochons are even less.

Chrome diopside is difficult to cut. Drenched in deep color, it needs perfect angles and polish to stay lively and bright.

With a hardness between 5 and 6 on the Mohs scale-compared to the 6.5 to 7 and 7 to 7.5 hardnesses respectively of tsavorite and chrome tourmaline-it could be a victim of wear and tear if set in rings. But don’t be too alarmed. After all, chrome diopside’s hardness is identical to that of opal, long a ring staple. So as long as you wear it in a non-abusive manner, it will last. At current prices, the rewards of owning chrome diopside far outweigh the risks.

Cat’s-Eye Chrysoberyl

Written by rdjadmin On May 2, 2013.

Visit a fine Japanese jewelry store today and you will very likely see a selection of cat’s-eye chrysoberyls sitting in the showcase reserved for men’s merchandise. Demand is so great for this phenomenon gem in sizes up to five carats that nearly all the supply of better small cat’s-eyes is sold there. “Japan has a lock on the market,” says one West Coast gem dealer.

Why the Japanese are so in love with cat’s-eye is a bit of a mystery. It could be the translucent honey color. Or it could be the mysterious slit of reflected white light that intersects the stone lengthwise when cut in cabochon form.

Also a mystery: the gem’s almost exclusive identification with men. As a result, cat’s eye is used mostly in rings, plus men’s accessories such as cuff links or tie tacks. Dealers aren’t really sure why this gem has such masculine appeal. They simply assume that cat’s-eye chrysoberyl’s “milk-and-honey” appearance lends itself more to men.

In this case, affluent men.

“There’s just good and bad in cat’s-eye,” explains a San Diego gem cutter, “and nothing in between. What’s more, the good is expensive, at least, in those five-carat-plus sizes men in this country prefer.”

Once above three carats, prices for fine to gem-grade cat’s-eye climb rapidly due to increasing rarity in larger sizes. For instance, a truly exceptional three-carat stone might cost several thousand dollars per carat in a jewelry store. Its ten-carat counterpart might cost three times more per carat.

That leaves American men pretty much confined to the four- to six-carat size range where increasing rarity and strong demand keep prices high for fine material. Most collectors don’t want to settle for less when it comes to this gem.

The “Eyes” Have It

Fine cat’s-eye must have a combination of elements — color, chatoyancy, clarity, translucency and proper cutting — to make it truly distinctive. Because so many factors come into play when judging cat’s eye, and so few stones measure up in the final run, the gem is for connoisseurs only.

“You’ve got to develop a feel for cat’s-eye,” says a New York cutter, “and that’s not always easy given the relative scarcity of fine material and the out-of-the-ordinary criteria by which it is judged.”

Unlike most gems, which depend on body color primarily to make it to connoisseur class, cat’s-eye has got to excel in two areas: color and chatoyancy. Briefly, chatoyancy is a gemological special effect by which light reflected from very fine, densely packed rutile fibers is concentrated in a crisp line, reminiscent of the iris of a cat’s eye, along the dome top of a stone when it is cut in cabochon form. Hence the name cat’s-eye.

Obviously, the “eye” of such a stone depends on the hand of the cutter. If the cab is cut too flat, the eye will appear too wide, wavy and ill-defined. If cut too high, the eye might appear too thin. And if poorly proportioned, the eye may be off-center or run slightly diagonally instead of lengthwise.

In short, a good “eye” is one that is centered, sharp and straight, without being pencil-thin. Viewed on top under a single light source the eye should stay bright and defined as the stone is rotated in the hand. Ideally, the “eye” should be free of coloration from the stone’s background. Often, however, there is bleed-through that gives the eye a yellowish or greenish cast, depending on which color predominates. Such interference is considered a drawback in connoisseur circles.

Honey Brown and Apple Green

After chatoyancy comes color. Cat’s-eye runs a color range from raw honey-brown to apple-green, with all sorts of mixtures in between. Although the men’s market tilts strongly toward the rich yellow-browns, a slight hint of green is acceptable to some men while greener stones find favor with women.

“For the most part,” one cutter says, “the honey colors come from Brazil, one of the two principal modern sources for cat’s-eye chrysoberyl. The other source, Sri Lanka, tends to produce more of the apple-green variety. However, the Sri Lankan stones tend to have more defined and silvery “eyes,” as well as greater luster.”

Luster is related to both hardness (an admirable 8.5 on the Mohs scale, one of the highest for any gem) and translucency, the degree to which light penetrates a stone. Cat’s-eye, also known as cymophane (from Greek words meaning to appear wave-like), should be neither opaque nor transparent. Opaque stones often lack the sensuousness of translucent stones while transparent and semi-transparent stones have overly watery color and dimmer, less defined “eyes”. In a properly translucent stone, the eye shines sharply with either a slightly milky-blue or silvery cast.

Carnelian

Written by rdjadmin On May 2, 2013.

In modern times, the highest value is placed on transparent gem crystals, which can be faceted to create brilliant gemstones. But in the ancient world, gems were worn as much for their power as their beauty.

That power could be enhanced through the power of words and images: gems engraved with a name, image, or phrase were considered to have a stronger influence as talismans.

That made chalcedony, the beautifully colored translucent quartz that could be precisely carved into seals and amulets, the rock star of the ancient world.

Different varieties of chalcedony, including carnelian, agate, and sard, were popular for rings and pendants because they made beautiful carving material.

But perhaps the most beautiful color was the orange-red colors known as carnelian, the zodiac gem for the sign of Virgo. Adding rich color to beads, inlay, seals, amulets, and cabochons, carnelian was one of the most popular gems of ancient times.

Mummies in ancient Egypt often wore necklaces with carved carnelian figures of the Gods, no doubt considered powerful amulets to protect the wearer during the journey to the spirit world.

One reason that carnelian has long been held in high esteem is that the prophet Mohammed wore, on the little finger of his right hand, a carnelian seal set in a silver ring.

As a result, there is a long tradition of revererance for carnelian, often engraved as a seal, in the Muslim world. Inman Jafar declared that the desires of one who wore a carnelian would be gratified. Traditional Persian jewelry often contained carnelians engraved with the name of one of the twelve imans.

Carnelian has long been associated with power in the secular world as well. Napolean wore a carnelian engraved with “The slave Abraham relying on the Merciful (God).”

Carnelian’s appeal continues today: now that gemstone beads have become fashionable, carnelian is once more in demand as a source of rich gem color at an affordable price.

Cambodian Zircon

Written by rdjadmin On May 2, 2013.

The mining news about Cambodian blue zircon is good and bad. The good news: availability remains the same. The bad news: availability remains the same.

Sorry, folks, but the best supply-side news about this zirconium silicate never seems good enough, especially at times like these when demand-side prospects for this gem are so promising. Just ask zircon devotees like Omi Nagpal, Omi Gems, Los Angeles, who are always on the lookout for stones with the deep, distinctive aftershave greenish-blues on which this gem’s reputation largely rests. Nagpal is searching hard for fine blue zircon as more designers and custom jewelers take a first or a fresh look at the gem that serves as the December birthstone choice. Why the surge of interest? Nagpal believes blue zircon is gaining attention thanks to the strong revival of pastel-blue stones like aquamarine as well as the sharp increases in prices of tanzanite.

Among aqua-types, blue zircon strikes us as the clear preference from a standpoint of looks and value. Zircon is a bargain-lover’s dream: a genuine rarity and a real steal. Nagpal showed us calibrated rounds whose blue blazed in a way that made one think of diamond-yet without the brilliance of the stones robbing them of color.

So why isn’t zircon more widely appreciated?

Spotty supply can’t take the rap for this gem’s lackluster reputation. Despite beauty and affordability, zircon is not without faults. Thankfully, they are small ones.

Brittle beauty

Deep-blue zircon is never plentiful because it is a one-source gem found mostly-some say only-in northwestern Cambodia at Rattanakiri some 40 kilometers from the Cambodian-Vietnamese border. True, zircon is also found in Sri Lanka, but its blues don’t have the bite and bounce of Southeast Asian stones. Indeed, Sri Lanka is known for zircon colors other than blue.

Zircon, like tanzanite, must be heated to attain the color for which it is prized. Since most Cambodian material winds up in Bangkok, it benefits from decades of Thai furnace finesse. One can’t help but wonder what might happen if Sri Lanka were to develop color-craft technology on a par with Thailand. Would the industry start to see better-grade blue zircon coming from that gem-rich country as well?

In any case, when used properly, oven alchemy turns blue-able zircons from reddish, orangy, and yellowish-browns to magnificent stable shades of a color that Nagpal describes as “menthol with a hint of mint.” “There’s always some green in the stone,” he continues, “but you wouldn’t call it a green gem.” He’s right. It’s blue. How ironic, then, that a gem most people now think of as blue-thanks to heating-derives its name from an Arabic color word zargoon meaning vermilion.

Heating does not guarantee glory for zircon. No more than 15 percent of Cambodia’s production is blue-able to the extent that Nagpal and other aficionados would like. Of course, part of the problem is size. Zircons need mass for class. So another 20 percent of the material is handicapped in terms of color intensity by the fact that it is cut in smaller sizes. At best, these stones tend to be pleasing rather than punchy. If you want the full wallop of blue zircon, you’ll have to go for sizes of 4 carats or more.

Although the color of fine Cambodian blue zircon can be likened to that of Paraiba tourmaline, it is probably better, says Philip Zahm, a zircon specialist based in Aptos, California, to compare this gem’s top hues to those of irradiated blue diamond. “Not only do the colors match,” Zahm says, “but zircon has dispersion near enough to that of diamond to add spectral fire and give extra oomph.”

Alas, zircons may pay a price for trips to the furnace. Although the relationship between heating and durability of gems dependent on this enhancement has not been systematically studied, some dealers suspect that heat worsens zircon’s brittleness all the while improving its beauty. With a hardness of 6-1/2 to 7, this gem is already a candidate for caution. But since it is particularly prone to abrading, specialists usually pack stones individually to keep them from knocking against each other and possibly scuffing or, worse, chipping one another. Keep the stone’s delicate nature in mind when designing settings and be careful when working with it. And don’t forget to tell customers to go easy on this stunner.

Blue zircon cut by award-winner cutter John Dyer of Precious Gemstones Co.

California Tourmaline

Written by rdjadmin On May 2, 2013.

Just as East Africa is the new frontier for gem mining today, America was the promised land for gems a century ago.

Certainly the discovery of tourmaline in Southern California in 1898 touched off as much excitement in the international jewelry market as did the discovery of tanzanite and tsavorite in Tanzania and Kenya in the 1960s.

Tiffany’s, which played a major role in elevating these two East African unknowns to collector gems, played an equally important role in the success of California tourmaline. Tiffany’s was among the world’s most adventurous jewelry stores, ever alert to new gem discoveries for which it could negotiate exclusive distribution rights.

How it managed to do so for California tourmaline would make a riveting movie, as filled with action and intrigue as any plot based on the state’s far more famous gold rush.

The Tourmaline Rush

At the turn of the century, California was to tourmaline what South Africa was to diamonds. Between 1898 and 1914, California’s San Diego county was unrivalled in production of this gem: Brazil, Burma, and Ceylon couldn’t touch it. In fact, close to 100 tons of tourmaline were produced by a single mine, the Himalaya Mine in Mesa Grande, 80 percent of the region’s production during the period.

Tiffany cornered the market in California’s tourmaline in a rather ungentlemanly manner. Gemologist J.L. Tannenbaum jumped the previous owner’s claim. Or so a 1904 court judgement against him suggests.

From the first time he laid eyes on the new California tourmaline, Tannenbaum was determined to possess it. He was unable to determine the exact location of the deposit so he journeyed to San Diego in 1902 and combed the countryside posing as a consumptive looking to buy a mountain cabin to improve his health. It may have improved his wealth instead: he found his ideal spot for a cabin next to the Himalaya mine. In no time at all, the “tubercular” man began his exercise regime, by vigorously working the Himalaya Mine. The mine’s owner, Gail Lewis, who Tannenbaum claimed had improperly filed his mining claim, promptly sued. Eventually, Tannenbaum paid Lewis $40,000 for the rights to the mine.

If Lewis could have foreseen the bonanza the mine was soon to yield, it’s doubtful he would have sold. According to various accounts, between the years 1902 and 1910, the mine produced more than half a million dollars in tourmaline.

The China Connection

California tourmaline had friends in high and faraway places. The most important was Empress Tzu Hsi of China. Her love of carved tourmalines made China the most important market for the gem at the turn of the century. When news of the new mine reached her court, she sent emissaries to investigate. The resulting Sino/san Diego tourmaline pacts contributed so much to the prosperity of both San Diego and the tourmaline miners that when the Chinese government collapsed in 1912, the tourmaline market collapsed also. The Empress chose to enter the afterlife resting upon a carved California tourmaline pillow.

The California tourmaline market today still is tied to the market for tourmaline carvings. Cutters like Gerhard Becker in Germany’s Idar Oberstein, the world center for gem carving, specialize in animal and bird figures, many carved from San Diego tourmaline.

For sure mining today is nothing like production in 1910, when rapid mining had already exhausted surface deposits and sent miners underground to reach deeper material. Since World War II, Brazil has been the world’s leading producer of tourmaline. But California has longevity and lore going for it. There aren’t many gems for which America can claim historical status as a leading producer.

Besides providing carving material, San Diego county is still an important locality for faceted tourmaline. The area is most famous for its pinks, ranging from hot bubblegum pinks to soft pastels. Like most pink tourmaline, they almost always have inclusions. The Himalaya Mine still produces bicolor pink and a few rare green tourmalines.


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