GemNotes

MINING DISASTER PUTS TANZANITE ON ENDANGERED LIST

El Niño monsoons destroyed mines and killed more than 100 miners in April in the gem areas of Meralani, Tanzania, threatening the supply of tanzanite over the next few months. At least a dozen tanzanite pits in an area called Block B have been completely shut down.

Enormous amounts of rain and poor tunnel construction caused the mines to cave in. Block B, which produces the highest percentage of tanzanites in the country, is in a low-lying area of the district. When the rains came, miners took to the pits for cover. But flash floods sent waves of water, along with the excavated dirt from the mines, cascading back down into the pits, burying the miners.

There’s no way to know the exact number of men killed, and there remains little hope for those who may be trapped. Because of the haphazard layout of the mines, one pit, 100 meters down, may go 300 meters across and sub-tunnel with another mine. There are no maps depicting where these tunnels go, no air pumps for ventilation and few water pumps to eliminate groundwater or rainwater. The mines that have suffered the most damage may never be reopened.

Tanzanite pits that didn’t collapse now stand empty. Miners are understandably reluctant to return to work knowing that their relatives and friends have been trapped or killed in the adjacent mines. The stench of decomposing bodies and the filth resulting from lack of sanitation fill the air.

Dana Schorr of Schorr Marketing & Sales, an importer in Santa Barbara, Calif., is currently in Arusha, Tanzania, near the mining area. Schorr predicts that U.S. jewelers “can expect 30% or higher increases in tanzanite prices.” Stones measuring 5 mm or less will be scarce but still available, Schorr says, adding that “stones of 6 mm and up will be extremely difficult to get.”

Just a short distance away in Kenya, the rainy season was heavier than the norm, and poor weather conditions put tsavorite mining on hold. The weather made it extremely difficult to get any consistent production, so miners typically spend the time exploring new test pits, washing test gravels and making repairs on the structures at the mines. Wet roads become impassable during the spring, especially for any heavy equipment, so it generally is impractical to mine. The discoverer of tsavorite, Campbell Bridges, president of Bridges Exploration Co. Ltd., says that “it’s all because of El Niño.” However, he notes, “there’s a bright side in that we have enough water for a year. It has created such a difference in the area – 2-meter-high elephant grass where before it was almost a desert. Now it looks like a tropical jungle, all within the last six months.”

Bridges says the Tanzanian disaster was inevitable. The El Niño rains and improper mining techniques were a deadly combination. “They should have removed the waste and followed mining engineering techniques to strengthen the shafts.” Bridges believes the government is responsible. “The Tanzanian mining authorities should have foreseen this. If [the miners] want to go as hard as they can in the shortest time possible, then [the government] should have a professional company come in, do it properly and employ the local people.” – Gary Roskin

COMPANY TO MINE YOGO SAPPHIRES

Pacific Cascade Mining of Canada has signed a four-year lease agreement with Roncor Inc. of Southern California, owner of sapphire deposits in Montana’s Yogo Gulch, to mine and market the natural blue gemstone.

Roncor and those to whom it leases rights have been mining Yogo Gulch for 12 years, with moderate success. While demand increased over the years, supply was dwindling. Four years ago, Cyprus Amax Minerals Co., a U.S. firm, tried its hand, but produced no more sapphire than its predecessors. It pulled out after two years.

Pacific Cascade has been test drilling to locate and analyze deposit reserves for the past year. It has found a number of new areas, all parallel to each other, that may hold lifetime reserves of the hitherto elusive sapphires. Now it plans to develop a larger commercial operation at Yogo.

Cascade, which anticipates substantial increases in production, will market to larger firms. It will continue to supply Roncor with goods for independent wholesale and retail jewelers.

MVI Marketing Ltd. of Beverly Hills, Calif., has done a market feasibility study under contract to Cascade. As it begins mining sapphire in Montana, Cascade will analyze the study and develop market strategies. – Gary Roskin

More Black Opals Head to U.S.

With economic turmoil hurting gem demand in Asia, more top-quality black opal is headed to the United States. Whether used as inlay, onlay or individual sets, some of the gems coming here are spectacular.

Nevertheless, quality opal remains relatively rare – blacks more so than whites. Mining efforts have been sluggish, and supply has tapered off since 1990. “The major problem our industry will face in the next decade is not one of market but of supply,” says Andrew Cody, president of the Australian Opal and Gem Industry Association (AOGIA). White Cliffs, Andamooka and Mintabie deposits are now “all but nonexistent,” he reports. Fortunately, Lightning Ridge – home to the finest black opal – remains active, thanks to the recent discovery of a productive zone called Coorcoran.

Shown below is a suite of exceptionally well-matched Lightning Ridge blacks with good play of reds, oranges, purples and blues. The ribbon pattern is quite dramatic when the stones are rocked back and forth. Their thick natural backing of gray protects them from damage and gives the face-up color its true dark background. Cut and fashioned from only one opal seam, the suite is made up of eight cabochons totaling 20.49 cts.; the large center stone alone is 10 cts. As a necklace, this suite should command $50,000 wholesale. The gems are available through JOEB Enterprises of Atlanta, Ga.

Extremely fine black opal also is found in inlays and intarsias. Some of the more impressive works in inlay come from Kabana in Albuquerque, N.M. Founded in 1975 by Stavros Eleftheriou, Kabana employs 250 jewelry artists; of the 15,000 designs in its collection, the most important are inlays of Lightning Ridge black opal. Choosing some of the most dramatic opals, Kabana sets the gems against matching-color black and white pearls, tanzanites and emeralds.

Idaho Opal and Gem Corp. in Pocatello is marketing fine-quality black opal intarsia designed by James Kaufman. It is believed that intarsia dates back to the Anasazi Indians, who lived in the American Southwest from roughly 450 to 1540 A.D. Intarsia involves onlaying gem materials to create mosaics, which can be set into rings, pendants and other jewelry or into decorative boxes. To hold down expenses, Idaho Opal contracts with skilled artists in China to create Kaufman’s pieces.

Choosing opals for a necklace, inlay or intarsia isn’t easy. The materials must be well-matched, the gems durable enough to be handled (thickness with no crazing), and the colors of high quality. It’s rare to find a grouping all cut from one stone.

Once stones are selected, they must be handled painstakingly because they’re easy to damage and hard to replace. Opal has a hardness of only 5.5 to 6.5 and its toughness, or resistance to breakage, is rated poor.

More complicated than inlay, intarsia usually involves four or more gem materials cut into 30 or more individual pieces of fairly thin slabs and slices, all of which must lie flat against each other. The intarsia is commonly glued to a solid gem backing for strength and consistency.

If your customers are looking for something unusual in colored gems, this is the year to draw their attention to black opal. Whether as inlay or intarsia, it’s sure to dazzle. – Gary Roskin

June Birthstones Do Wonderful Things with Light

June is the only month with three birthstones. Fittingly, since June has the most hours of daylight, all three stones – pearl, alexandrite and moonstone – transform light into something special.

With pearl, the light phenomenon is a magical “orient” iridescence: The light traveling through layers of nacre creates a rainbow-like appearance over the surface of the gem. Alexandrites change colors. Through selective absorption of light, they alternate from green in daylight to red in candle light. Moonstone is adularescent, showing a billowy light floating across the surface of the domed gem. Don’t be surprised if your customers have a hard time making a choice among these three beautiful stones. In fact, they might want them all.

PEARLS

Pearls, the “tears of the sea,” are the byproduct of a living creature, a mollusk. In the attempt to smooth over a foreign object that has penetrated a mollusk’s shell, the mollusk secretes nacre, the same substance it uses to line the shell’s interior. Slowly, over several years, the nacre layers (of aragonite and calcite) grow into a pearl.

Before this century, rare natural pearls were the only ones available. They were extraordinarily valuable. In 1916, the elegant building that Cartier owns today on New York’s Fifth Avenue was purchased with two single strands of natural pearls.

The intrusion in natural pearls begins as a tiny, even microscopic, irritant. Because of this small starting point, natural pearls can range in size from very small “seed” pearls to very large (and very rare) 8, 9 and 10+ mm sizes. The important quality factor is that they’re natural; luster, spotting, roundness, color and even size are all secondary to the fact that Mother Nature produced the entire bead.

Natural pearls once were found in abundance in the Persian Gulf. Oil spills and wars put an end to that. Most natural pearls today originate in the Gulf of Manaar (off the coast of Sri Lanka), Australia, Malaysia, New Guinea, Venezuela and the Gulf of Mexico. Natural abalone pearls are becoming popular, with the best coming from New Zealand. Natural pink pearls from the freshwater rivers of Texas are harvested every year, but in such small numbers that all are sold in the U.S.

Europeans and Middle Easterners prize natural pearls more than do Americans. Families pass them down from generation to generation. Americans, meanwhile, focus on the cultured pearl. Although only a relatively thin layer of natural nacre makes up the cultured pearl, its economical price and standard sizes, as well as the ease with which it can be matched into strands, make it more important for the huge American market than the natural pearl.

The giant conch – the shell used to make cameos – also produces a natural bead. Because it isn’t created by layers of nacre, the “conch pearl” isn’t considered a genuine pearl. However, its beautiful pink color with flame-like surface pattern makes it a desired gem in its own right. The Melo Melo pearl from the conch in Southeast Asia produces a “pearl” that can grow to 30 mm or larger.

Saltwater cultured pearls. Kokichi Mikimoto first developed cultured pearls in 1893 when he successfully implanted a bead in a mollusk. His achievement was quite a breakthrough, given the trauma, infection and natural predators that can wipe out so many beaded oysters. Today, the Japanese implant mother-of-pearl beads and use the pinctada martensii, now called “akoya” mussel, in their saltwater bays. The industry is a huge success.

Ironically, the mother-of-pearl bead that works best for saltwater cultured pearls comes from Mississippi River freshwater shells. These mollusks grow in colder waters, creating thin, more compact layers of nacre than shells from other countries. This more durable nacre gives rise to a more durable bead and more rounded pearl. Only a maximum of 0.5 mm of nacre grows over the bead, producing sizes up to 8.5 mm.

Chinese pearls. The Chinese have been culturing mantle-tissue nucleated freshwater pearls for decades. Some look like the Biwa pearls from Lake Biwa, Japan, famous for their pleasing shapes and multi-pastels. Within the past few years, the Chinese have been culturing freshwater bead-nucleated round pearls, as well as saltwater bead-nucleated pearls.

While China has produced its own shells for bead nuclei, the Chinese also use U.S. beads. Current production yields maximum sizes around 7 to 8 mm. Freshwater cultured rounds can grow as large as 9 to 10 mm, with drops measuring over 12 mm.

Freshwater cultured pearls. These are created in the same way as saltwater pearls, except different mussels and beads are used. Freshwater mussels tend to be larger and can live longer than the saltwater mollusks, and therefore can be used more than once to grow pearls. When freshwater pearls were first cultured, mantle tissue – a portion of the actual mussel – was implanted to create a somewhat free-form pearl. Today, mother-of-pearl beads are used to create all types of shapes.

South Seas. The mussel used in Tahiti, New Zealand, Burma and Indonesia is the relatively large pinctada margaritifera. Because of its size, the pearl it produces grows from 9 to 18 mm. The shell color dictates pearl color, which ranges from white to black, with golden and gray shades occurring as well.

Weight. Describing the size or weight of a pearl is quite different from describing a transparent gem. While some merchants make it easier to relate by weighing single pearls in carats, most will use the traditional terms of momme and grain for describing weight.

One momme = 3.75 grams (18.75 ct.)

One grain = 0.25 carats (“4 grainer” = 1 carat)

Quality. Quality depends on a combination of several factors, including the following:

Luster. Luster is created by the thickness of the nacreous layers. More light passes through thinner layers, reflecting back and creating a higher luster with more shine than pearls with thick nacreous layers. The Japanese saltwater mollusks live in cooler waters and grow thinner layers of nacre than those in the South Seas. Warmer waters there cause faster and thicker growth, and therefore a somewhat dull luster.

Nacre. The amount and quality of nacre are important for the pearls’ longevity. Pearls are a delicate gem that can be attacked by perfumes, body acids and normal wear. The pearl’s hardness is only 3 to 4, so many objects can scratch the nacre. Japanese cultured pearls of fine quality will have approximately 0.5 mm of nacre, while South Seas pearls can typically have 2.5 mm of nacre. Anything less in either case will lead to faster deterioration. Many Chinese and some Japanese pearls have relatively thin nacreous layers. Be sure to inspect each pearl for dangerously thin nacre.

Since most cultured pearls are drilled at least once, you actually can see the thickness of the nacre by looking down the drill hole with a loupe. Just below the nacreous surface is a layer of dark organic binding material called conchiolin. If you can see the conchiolin, then you can judge the nacre’s thickness. If you cannot see the conchiolin, the pearl has probably been dyed or bleached.

You also can determine nacre thickness by holding a strong light behind the pearl while rotating it and watching for the layers of a mother-of-pearl bead. If you see the layers, the nacre is much too thin to be of lasting quality. A pearl that “blinks at you” as you rotate it, showing light and then dark, also is a sign of thin nacre.

Blemishes. As you would expect, the number, size, nature, color and location of blemishes are all significant. Just as in diamond grading, all five factors are important.

Size. Round Japanese cultured pearls usually don’t grow larger than 7 or 8 mm. Therefore, a 9-mm cultured pearl would be rare – and valuable. But a 9-mm South Seas cultured pearl is small and won’t command a high price based on size.

Shape. If it’s round you want, it should be as round as it can get. A perfectly round, spherical pearl will roll across a table without wavering. But if you’re interested in a fancy shape, then freshwater pearls are your best bet. American Pearl Company has been growing fancy-shaped pearls for years with the jewelry designer in mind. This year, it offers a triangular-shaped pearl along with all of the natural and cultured shapes.

Color. Colors can vary in acceptance depending upon how well the pearl complements a customer’s skin tone. What may be valued in one culture may not be in another. Usually color is described using body color plus the overtone.

Orient is the iridescent spectral colors seen coming from the surface as you rotate a pearl. Overtone is usually a smaller single color, different from the body color, which appears stationary as you move the pearl, as if someone had painted it onto the surface.

Pink rosés are the most popular. Colored pearls, such as goldens and blacks, gain value as the color becomes more obvious. Black pearls should have an iridescence of rainbow colors. A predominant blue or green overtone is most valued.

Colors can be enhanced by dyes and irradiation. Most saltwater cultured pearls are dyed or bleached. The conchiolin layer is whitened using hydrogen peroxide to even out the white body color. Pink and peach also are added to create more colorful body colors. Irradiation is used to make spotted pearls black, covering up uneven body color.

Matching. Matching is a value factor for all gems. If two or more match, they’re more valuable as a set then as single gems.

Pearl vocabulary. A pearl attached to the inside shell of a mollusk is called a blister pearl. Cultured blister pearls are created by attaching a round, half or fancy-shaped bead to the inside shell. The pearl, along with its attached shell backing, is cut away from the remainder of the shell.

Mabé is a Japanese term for half pearls. The attached bead is removed from the shell and a new shell back is cemented to the created pearl.

Majorica pearl is an imitation, a bead that’s been coated with a material resembling the nacre of a natural pearl.

Wholesale prices. Natural pearls: Fine quality, cream, 6-7 mm, $700-1,800 each.

South Seas cultured: Fine quality, white, 12-13 mm, $1,500-2,200.

Tahitian cultured: Fine quality, black, 12-13 mm, $1600-2,200.

Mabés: Fine quality, white, 14-15 mm, $70-95.

ALEXANDRITE

From the Ural mountains of Russia comes a gem that undergoes a dramatic change from grass green in daylight to raspberry red under artificial light. Alexandrites also are found in Sri Lanka and Brazil. Brazilian gems turn from purplish red to bluish green, while those from Sri Lanka go from desaturated colors like brownish purple to grayish bluish green.

Alexandrite is not the only gem that can change color, of course; garnet, sapphire and spinel do so as well. (Many people feel that tanzanite is a color-change gem, too, but since its two colors are similar in spectrum – blue and purple – it technically undergoes only a “color shift.” )

Alexandrite was discovered in the emerald mines of the Ural mountains in the mid 1800s, when Queen Alexandra was Russia’s reigning monarch. Thus its name. The stone is a chrysoberyl, a beryllium aluminum oxide. Other chrysoberyls include transparent colors of yellows, browns and greens, as well as a sought after honey-colored cat’s eye.

As a transparent gem, quality is based on the four Cs, as well as its phenomenon. Cutting a gem to maximize its phenomenon is more important than orienting the cut for proper angles or weight retention, or reducing inclusions for better clarity, although these must be considered as well.

Most natural alexandrites contain inclusions that help to identify their origin. There also are fine synthetics in the market – flux alexandrites as well as hydrothermal ones. The latter is produced with very few, if any, inclusions. On the other hand, flux synthetics seem to have more than their fair share of unique characteristics, including platinum platelets, needles and flux.

The going wholesale price for fine quality alexandrite is $4,000-$6,000 for a one- to two-carat stone.

MOONSTONE

Moonstone, one of the phenomenal orthoclase feldspars, possesses the unique ability to turn light into a billowy reflection that rolls across its domed surface. To some, the reflection is reminiscent of moonlight. Most commonly the light is white; its most prized color is blue or a multi-hued “rainbow.” On rare occasions, when the light reflects in an even-directional plane, a cat’s-eye moonstone occurs.

The gem, found in Sri Lanka, India and Burma, is relatively inexpensive, costing only $10 to $20 per carat wholesale. A fairly popular version contains a carving of the moon as a man’s smiling face.

Astrological Birthstones

If you were born any day from June 1 through June 20, your astrological sign is Gemini and your zodiacal birthstone is the agate. If you were born any day from June 21 through July 20, your astrological sign is Cancer and emerald is your zodiacal gem. – Gary Roskin

Video features Cultured Pearls

The Cultured Pearl Information Center (CPIC) has released “Cultured Pearls, Legendary Gems,” a 37-minute educational video about the Japanese Akoya pearl. Two years in the making, the video traces the history of pearls from ancient times through the present day, focusing on the details of oyster implantation, farming and harvesting. There is also an easy-to-understand section on judging the quality of pearls. The video can serve as both an eductional tool for sales staff and a buying guide for consumers. Copies sell for $30 and are available from the CPIC at (212) 688-5580.

C3 Gets Patent for Moissanite

C3, maker of the new diamond substitute moissanite, announced it has received “a patent for silicon carbide gemstones.” Jeff Hunter, company president and CEO, says the patent “establishes C3 as the exclusive source for lab-created moissanite gemstones.” It gives C3 exclusive rights to manufacture, use and sell lab-created moissanite in the U.S. (Rights to use pass to any buyer.) To date, only samples of synthetic moissanite are available to the trade, with first priority going to jewelers who have purchased the C3 moissanite tester.

C3 is a publicly owned company based in the Research Triangle Park area of North Carolina.

IGI OFFERS MOISSANITE TESTER

The International Gemological Institute in New York City announced the availability of a “simple and inexpensive scratch test” to separate diamond from synthetic moissanite. While IGI’s laboratory would never use such a destructive test, many jewelers and pawnbrokers still appreciate the ease and small cost of a hardness tester.

Educated users can find hardness points helpful, especially to identify nontransparent ornamental gem carvings. But several nondestructive tests can be performed to identify transparent gems and especially the new synthetic moissanite.

Jerry Ehrenwald, president of IGI, says the institute offers this tester as “an accommodation to the trade” for those who still use this type of identification tool. He did not disclose the nature of the actual tester material, but said its hardness is about 9.5 so that it will scratch synthetic moissanite, but not a diamond. The hardness point tester retails for $29.95; a pen-like holder is $19.95.

Hope Diamond on A&E

The Hope Diamond made a guest appearance on the A&E channel Feb. 1. Approximately 1 million viewers were watching as A&E’s “Treasure” series focused on the Hope Diamond and the services of GIA’s Gem Trade Laboratory. GIA diamond authority John King spoke of his role – and that of his fellow gem specialists – in examining and grading the Hope Diamond in 1988 at the Smithsonian Institution’s Natural History Museum in Washington. In 1997, King returned to Washington with his team to examine and grade many of the other important diamonds residing in the Smithsonian’s newly opened Gem and Mineral Hall.