GemNotes

Tourmaline Find Generates Excitement

A recent find of tourmaline in Nigeria is the talk of the gem world. The stones, ranging from light pinks to deep purples, were discovered on farmland about 25 miles west of the border with Benin.

Measuring less than a square kilometer in a small river basin, the deposit was mined so quickly it’s already depleted, according to Bill Larson, owner of Pala International in Fallbrook, Calif. “It was a once-in-a-lifetime pocket,” says Bill Barker of Barker & Co. in Scottsdale, Ariz. “The color and clarity is incredible. We have some strawberry colors that are just beautiful.”

Michael Gray, master gem cutter, owner of Graystone Enterprises in Missoula, Mont., and partner in Coast to Coast Rare Stones, says the find produced large quantities – some 600 kilograms. “Germany was full of the material,” he reported in November after returning from the Munich Gem and Mineral Show. It’s also keeping cutters in Idar-Oberstein busy, according to Constantin Wild, an Idar gem cutter and wholesaler.

Larson and others, including Barker, have partnered in the purchase of 25,000 grams of top-quality material, which he hopes will translate into 30,000 to 40,000 finished carats. Much of this is being cut in Idar and China, with some cut in the United States.

Barker reports that the majority of rough is bead, cabochon, and carving grade, with a small percentage, possibly one-third, being facet grade. From the nice, clean material he’s seen so far, Gray expects an average of 20% weight recovery.

While much of it is said to be of natural color, there are good numbers of crystals that have a slight brownish tint, which apparently can be driven off with minor heat treatment.

“We bought some very fine-quality pieces,” some of which showed “stained or green skin,” says Barker. When the skin is removed, the gem reveals a “beautiful cranberry to pink, mauve pink, and a small fraction of true rubellite [red] to a slightly orangy red,” which he feels is the best. There are pinkish-orange gems as well as straight orange tourmalines in the lot.

Even though the quality strikes many gem dealers as outstanding, Gray suggests that the average prices of the material during the Tucson Gem and Mineral Shows next month will be marked at a relatively low $60 to $100 per carat because, he says, “there is so much of it.” At the moment, wholesale rough reportedly is inexpensive, including some nice, large, flawless crystals weighing up to 100 cts.

Of course, the more rare colors as well as larger and finer gems will bring much higher prices. “There are also a few rare multicolor stones, usually brownish-pink, white, and green,” says Wild. “I even own one that has five colors in one piece: pink, white, green, purple, and blue!”

The Nigerian tourmaline rough has a rounded, water-worn shape. But there are also sharp crystals available, which means that they were found near or at a primary source.

According to Barker and Larson, all indications point to this deposit as having been the alluvial source of a completely eroded-away pegmatite. Such has been the case in Namibian tourmaline deposits, where the original outcropping was completely eroded away.

Getting a head start on the competition by using their Web sites, some wholesale stone dealers are already advertising these gems, describing them as “purple-pink verging on red,” “hot reddish-pink,” and “deep violet pink.”

Unmasking the Marque of De Beers

Since last summer, De Beers has test-marketed its branded diamonds in the Boodle & Dunthorne retail jewelry chain in Manchester, England. Using the latest in electron-beam lithography, De Beers is marking its logo and a serial number directly onto the table of the diamond.

After hearing all the talk about De Beers’ branding, diamond cutter Dieter Hahn of Idar-Oberstein, Germany, wanted to see exactly what the brand looked like. Unable to obtain a marked gem directly from De Beers, he paid retail at Boodle & Dunthorne for an engagement ring containing a 0.40-ct. round brilliant. In October, he displayed the “De Beers Marque” diamond at Intergem ’98 in Idar-Oberstein.

Hahn’s findings. The “Marque” is not your standard inscription of black letters laser-burned onto the surface of the stone. Instead, it has the appearance of the old “sputtering” label, transparent and three-dimensional. (Sputtering is a thin-film process used to deposit metals such as aluminum, gold, and titanium, dielectrics such as Teflon, and pure elements such as carbon.)

Hahn’s curiosity prompted him to study the marking. “After coating the diamond with carbon, we investigated the sample, looking for the presence of other elements. In fact, there were none, only carbon. So we concluded that ion implantation is not likely.”

His study went further. “For the topographic investigation under different magnifications, we coated the sample with gold,” says Hahn. “By tilting the sample, we found that the letters are not a coating, because of the lack of depth. The ground of the letters is very smooth, so laser engraving is also excluded. That’s why we assume De Beers uses electron-beam lithography.”

De Beers officials won’t say what process they use or reveal the size of the Marque. The Gemological Institute of America’s Gem Trade Lab has obtained several De Beers branded diamonds with Marques of varying sizes. Some are easily visible at 10x, while others can’t be detected at that magnification. The diamond Hahn purchased has a Marque readily visible at 10x.

The guarantee. Accompanying Hahn’s diamond was the De Beers Marque brochure, which says the Marque is “reserved for the world’s finest diamonds.” Explaining how diamonds have been chosen for this inscription, the brochure notes that the Marque “now takes the judging of diamonds one significant step further. We recognize that it is the interaction of a diamond’s individual characteristics that is important. Only in the finest diamonds do these characteristics truly interact to create intense fire and brilliance. It is these rare diamonds that we select to bear our Marque.”

Many consumers already are familiar with the De Beers name. To reiterate this, the brochure states that “for over a hundred years we have been dedicated solely to diamonds and have set the standards for others to follow. Each year, our Master Diamond Selectors examine close to three-quarters of the world’s diamonds. This unrivaled experience allows us to look beyond the traditional 4Cs and identify diamonds of true quality and brilliance.”

The brochure concludes, “You do not have to be an expert to be sure that you have found a diamond of the highest quality. De Beers, the world’s diamond experts, have identified them for you.”

Diamonds That Change Color – Naturally

If you’re interested in the rare and unusual, you’ll be fascinated with a recent diamond find in China. A small, primitive mine there is producing melee in fancy colors of pinks, blues, purples, and oranges. It also produces thermochromic stones (which change color on exposure to heat) and “chameleons” (which change color from exposure to light and/or heat).

“Chameleon” diamonds generally change color from fancy yellow to an olive color – fancy grayish-yellowish-green – under some very unusual circumstances. The phenomenon was discovered by mistake, reports Moti Weisbrot, managing director of First Diamond Group Ltd., Hong Kong. “When the first parcel of diamonds was sent from the polishing factory to our New York office, my uncle Isaac Abramcik called to tell me that the ‘yellow’ goods I’d sent are of a very nice fancy yellow color.” A surprised Weisbrot replied, “What yellow? I sent you the first production of the green colors.” Most “chameleon” diamonds are discovered this way.

When a parcel of chameleons is first opened after being kept in complete darkness for more than 24 hours, upon first glance the diamonds appear a very pure yellow. But as the stones absorb light, they change (within a few seconds to a few minutes) to a dark olive green color.

The output of the mine, according to Weisbrot, is mostly fancy or near-fancy color, 95% of the stones green or greenish-yellow. A small number of these are chameleon. About 4% to 5% of the rest of the mine’s “fancy-color” output consists of “capes” (light yellows), browns, “whites,” and grays, with a very small percentage of oranges, pinks, purples, golds, blues, and intense and vivid yellows.

Some of the fancy yellow diamonds react to heat. “They are very difficult to match,” says Abramcik. In the morning when they’re taken out of the safe, they’re yellow. By the next hour, they begin to look bronze or golden. And they get darker as the day goes by. When kept under the hot spotlights of a display case or grading table, they slowly shift their hue and tone, becoming darker and more reddish-yellow (orangy/golden/bronze-colored).

The Chinese chameleons are being marketed by the Rolling Stone Co. of New York. The price for 0.01 ct. to 0.10 ct., VVS-VS, is $450 and up for the color-changing diamonds (greenish-yellow) and for all other colors, except blue, pink, and purple. The most common finished sizes are 0.01 to 0.07 ct. Larger sizes are priced at $900 for 0.10 to 0.18 ct., $1,300 for 0.18 to 0.28 ct., and $1,850 for 0.28 to 0.38 ct. Diamonds larger then these are sold as single stones, at different prices.

Weisbrot says, “We will show our production at the February Tucson show, including some outstanding large fancy green diamonds.”

Weisbrot is one of the developers of the Shanghai International Diamond Exchange Center, a $66 million project that is reported to be the official diamond bourse of the People’s Republic of China.

GIA Examining One-of-a-Kind Diamond

Currently being studied by the Gemological Institute of America’s Gem Trade Lab is the world’s only known alexandrite-like change-of-color diamond, a 0.52-ct. synthetic made by Ultimate Created Diamonds (UCD), Golden, Colo. It changes from a slightly brownish, slightly yellowish-green to a slightly brownish-purple. According to Alex Grizenko, president of Russian Colored Stones and UCD, this synthetic gem is the only true change-of-color diamond GIA researchers have been able to verify.

“We make lots of colors,” says Grizenko. The list is impressive, including yellow, yellow-green, red, pink, peach, and now a true alexandrite-like bluish green synthetic diamond that changes to reddish-purple. “Every color has its own recipe. Some recipes are simple, some are complex. This one [the alexandrite-like change] is a complex one. The yellows are the easiest; the colorless is complex. The greens are complex, although a little less so.”

The real breakthrough here is that once the “recipe” is determined, it can be reproduced in the same color in quantity. Says Grizenko, “When a manufacturer or designer wants 24 of this color, great!” But if UCD does not have the right color, the company can experiment. “We’re not quite like a paint company, but as we get more recipes, we can be.”

According to Dr. Ilene Reinitz, research gemologist at GIA’s Gem Trade Lab in New York, the synthetic has very typical synthetic diamond features: a squarish cloud of pinpoints, a green fluorescent cross in the middle of the cloud – seen in long-wave and short-wave ultraviolet light – cubic graining, and an interesting spectrum “showing the same steep slope through the orange, right where daylight and incandescent light have their sharpest difference.” This would account for their obvious color change when viewed under different light sources.

Baert Fired By Diamond High Council

Walter Baert, who played a key role in raising international awareness of Antwerp’s Diamond High Council and diamond industry, was fired in October. He was its public relations manager for 15 years.

The announcement was made by the council’s executive committee. It followed disagreements involving Baert, the council, and its new general manager, Jan De Kessel.

Baert handled all of the council’s public relations outside of Belgium and was the face of the council and Antwerp’s diamond industry to the global jewelry industry.

He and his staff organized Diamond High Council exhibitions, meetings with the world press, and diamond trade conferences at international jewelry fairs. He also helped create and organize the popular biennial international “From the Treasury” exhibitions in Antwerp.

The Diamond High Council thanked Baert for his “dedication and important services [to] the diamond sector.” De Kessel will handle public relations until Baert’s successor is selected. – William George Shuster

Moissanite Shipments Up Six-Fold

Synthetic moissanite manufacturer C3 Inc., Research Triangle Park, N.C., shipped 6,500 cts. in the third quarter of 1998, a six-fold increase over the previous quarter’s shipments. The average price per carat was estimated at $178. The company stepped up production sharply to meet increased retail demand.

C3’s supplier, Cree Research, has broken the 2-in. crystal barrier by creating a usable 3-in. crystal. This size is expected to produce twice as many gemstones as the 2-in. crystal. Additionally, C3 has expanded its domestic market by adding 19 retail outlets, mainly in the Southeast but also including three Midwestern stores and one California location. This brings the number of domestic retail outlets to 52. Meanwhile, C3 is looking abroad, signing a marketing agreement with Moissanite Indonesia Ltd.

C3 was expected to ship an estimated 10,000 cts. of moissanite in the fourth quarter. For more information, visit C3’s Web site: www.moissanite.com.

Robert Kane Leaves Gübelin Lab

Robert E. Kane has left the Gübelin Gemmological Laboratory in Lucerne, Switzerland, after two years as its director. Kane says he resigned because he wanted to spend more time on gemstone research projects. He’s also “considering several exciting offers, but I’ve not made any final decisions.”

For more than 50 years, the Gübelin lab has been the lab of choice for auction houses, internationally famous stone dealers, and jewelry salons requesting reports that identify a gem’s country of origin.

Dietmar Schwarz and George Bosshart, two respected longtime staff gemologists and research scientists, remain at the Gübelin laboratory.

Tanzanite Prices Climbing

In recent months, wholesale prices of tanzanite have soared by well over 50%. The average price for a 2-ct. gem last July was about $220 to $240 per carat. Today, the same stone fetches $350 and up.

Prices started rising immediately after the mine flooding last summer in Tanzania. Now that the mines are repaired and back in operation, you’d expect more reasonable prices by this point. In fact, the price increase seems to stem less from the disaster than from a shortage of daily production.

For years, the industry has heard the cry that supply won’t last, and that point may finally have arrived. Some 20 buyers are sitting at the mines waiting to purchase 500 to 700 cts. a day. Yet total production is reportedly just 200 cts., according to Aseem Singh, president of STS, one of the largest tanzanite suppliers in New York. With tanzanite’s popularity still on the rise, most buyers are eager to obtain whatever quantities they can. They’re willing to bid up the price to get their quota of available goods.

North American Beauties

Starting with this issue, Gem Notes will highlight gemstones found in North America, including Mexico, the United States, and Canada. While normally the department focuses on gems found in Third World countries in Africa, South America, and Asia, we’ll be paying special attention throughout 1999 to what’s being found right in our own backyard. We start our series with Arizona amethyst, a recent rediscovery of the Four Peaks Mine.

‘Siberian’ Amethyst from Arizona

Reopened last year after two decades of closure, Four Peaks, North America’s foremost amethyst mine, now produces some 1,000 to 1,500 lbs. of fine-quality gem rough each month. The first faceted gems from the legendary site 25 miles northeast of Phoenix received rave reviews last February at the American Gem Trade Association Gem Fair in Tucson (JCK, April 1998, p. 72).

For Kurt Cavano, managing partner of Four Peaks Mining Co. in Phoenix, buying the mine was a matter of being at the right place at the right time. “When we learned that Four Peaks was for sale at the 1997 Tucson show, we became excited that we could potentially own an historic property,” recalls Cavano. After purchasing the mine, Cavano contracted with Jack Lowell of Colorado Gem and Mineral Mining to process the rough and formed a joint venture with Mike and Jerry Romanella of Commercial Mineral Co. to cut and market the final product.

Four Peaks was discovered at the turn of the century by gold prospector Jim McDaniels. He was actually looking for the “Lost Dutchman” gold mine, which according to legend held a huge deposit of the highest-grade gold. McDaniels stumbled upon amethyst instead. (The secret of the gold died with the 19th-century Dutch prospector who discovered it.)

Four Peaks is part of the Mazatzal mountain range, rising out of the Arizona desert to a height of nearly 8,000 ft. These four majestic peaks line its southernmost face. The mine is at 7,200 ft., almost at the summit of the fourth peak. Because of the difficulties of mining in such a remote wilderness, it’s been closed for the past two decades. “There’s nothing easy about what we are doing at Four Peaks,” says Cavano. “We got a late start last year because of the greater snow pack from El Niño.”

Mining began in late April. Monthly operations consist of four 4-day, two-person shifts. With no road access, everything is flown in and out by helicopter. No more than 400 lbs. of rough can come out, or that amount of food, water, and equipment can go in, at any one time. “We’re excited about the potential of the mine, but it isn’t easy,” says Cavano. “If it were, anyone could have done it.”

The mine produces natural color amethyst, sometimes as large as several hundred carats. Colors range from the pale pinks and lilacs through the violets and deep reddish-purples. The latter is the most valued color, which many say rivals the very finest quality from the Russian Urals. There’s also a smoky, deep violet color that is unique to the Four Peaks mine. Some stones contain a bronze hematite inclusion, giving them a somewhat aventurescent (glittery) appearance.

Four Peaks amethyst is valued not only for its color, but also for its ease of identification. Natural amethyst has been difficult to distinguish from synthetic stones ever since commercial production of synthetic amethyst began in the late 1970s. The growing proliferation of synthetic amethyst came to light in 1996, when AGTA and Asian Institute of Gemological Sciences labs found large amounts of synthetics salted into parcels labeled as natural. Ken Scarratt, then director of the AIGS lab, discovered that 40% to 60% of supposedly natural gems were actually synthetic.

The Four Peaks natural amethyst has a readily identifiable natural color zoning, which producers of synthetics try to eliminate.

It’s also characterized by a “Brazil-law twinning” crystal structure, easily spotted with an inexpensive polariscope.