GREEN STONES: BEYOND EMERALD AND PERIDOT

When customers think green gems, they envision emerald, and perhaps peridot. But there’s a broad range of alternatives to recommend, and they can be much more affordable than emeralds. If you know the other greens, you increase your chances of making a sale.

The chromium factor. Chromium, a metallic element, makes rubies red and emeralds green. In other gem varieties, this natural coloring agent enriches the ordinary green color. Take green tourmaline, for example. With the presence of chromium, the color is superior and the stone becomes more expensive. A 3-ct. fine color green tourmaline will wholesale for about $100 per carat. But with chrome tourmaline, the color and rarity will affect the price, and a fine 3-ct. stone jumps to $600 per carat.

Tsavorite is another gem that owes its rich color to chromium. It was not until the early 1960s that it was discovered in Kenya. The industry credits Campbell Bridges, president of Bridges Exploration Co. in Nairobi, with developing the tsavorite trade. From the early days of its existence, Bridges envisioned tsavorite as the next emerald. But it never gained enough momentum for this to occur, partly because supplies are limited. However, through the years this gem has gained in popularity, and recent controversies over emerald enhancement have given it an added boost. Tsavorite is a natural gemstone, not known to be enhanced in any way.

Hot sellers of 1998. Chrome diopside is mined in a remote area in the Russian state of Sakha. This is the only mine in the world where diopside contains chromium. Because of the location, supply is limited. Chrome diopside is usually very saturated in color. In fact, its only drawback may be in the oversaturation that can occur. Cutting is very tricky. To maximize the color potential of this gem, it takes a skilled cutter and a willingness to endure great waste.

Chrome diopside was a big seller in February at the Tucson gem shows. Although this gem has been available for many years, the trade never embraced it because of the low hardness on the Mohs scale – 5 1/2 to 6. Many dealers considered it too soft. But through the years, jewelers have become more accepting of softer gemstones, including tanzanite (6 to 7), apatite (5 to 5 1/2), and benitoite (6 to 6 1/2 ).

Marketing by a few gem dealers has contributed to chrome diopside’s recent popularity. Columbia Gem House in Vancouver, Wash., a key player in the Russian chrome diopside distribution chain, has aggressively marketed it. Another contributing factor is the affordable price, especially in light of the limited supply. At wholesale, these gems sell for $20 to $60 per carat, with most gems between $20 and $40 per carat. Gems are available up to 5 cts. However, stones more than 3 cts. tend to be too dark.

Demantoid has surged in popularity with new finds in the Ural Mountains in Russia and in Namibia, Africa. The stone, discovered in the Urals in the late 1860s, was popular in Edwardian period jewelry (1890-1915). By 1900, demantoid mining had ceased, and it was destined to become strictly a collector’s stone. When a demantoid surfaces at an auction, the bidding is usually aggressive.

The colors of the demantoid discovered in deposits in Namibia last year were more uniform yellowish green – not the prized color of the Russian material. The gems were big, though, some coming to market in previously unheard-of sizes, greater than 3 cts. The new find in Russia also generated excitement. Josh Hall, vice president of Pala International in Fallbrook, Calif., reported brisk sales in Tucson.

A beauty from Mali. Grandite garnet, a mixture of andradite and grossularite mined in Mali, is becoming better known. The color ranges from a yellowish green to a pure green and resembles demantoid garnet, so it has great appeal. The green color is rarer, thus prices are higher. Prices for a fine-quality 1-ct. gem will be $300 to $400 per carat.

Green Choices Fine Quality – Average Wholesale Price per Carat

Emerald $1,500
Demantoid $1,350
Tsavorite $750
Grandite garnet $350
Chrome tourmaline $275
Green tourmaline $60
Green sapphire $60
Green beryl $55
Green chrysoberyl $50
Green grossular garnet $40
Peridot $35
Green apatite $30
Green quartz $5

Apatite, enjoying a new popularity, comes in green and other colors and is mined in Sri Lanka, Burma, Bohemia, Mexico, Maine, and elsewhere. Because its hardness is only 5 to 5 1/2, it didn’t have much appeal for jewelry designers. To this day, it remains on the Gemological Institute of America’s “B” chart. In the past, the gem was only a few dollars per carat.

It’s tough to determine exactly when the apatite boom began. The Paraíba tourmaline discovery may have something to do with its new success. Paraíba tourmaline is known for its bright neon colors. Although apatite is certainly not a threat to Paraíba, the finer-quality gems do exhibit somewhat of a neon appearance. Paraíba is in a class by itself, but the bright green apatite gems are a great, affordable alternative. Once jewelers and consumers got accustomed to the softness of apatite, popularity grew. Prices jumped tremendously in only a few years. Few would have believed that a fine-quality apatite today would be worth $50 per carat. The highest price for apatite seen in Tucson this year was $100 per carat for an extra-fine specimen.

For those interested in alexandrite, there’s always the less expensive, non-color-changing chrysoberyl. It’s the same species as alexandrite, without the color change. It’s a gem that can fit into any budget. The average price of a fine green chrysoberyl is only $50 per carat, although some can be more expensive.

Prices sink a stone. Green sapphire almost had its day of glory about 15 years ago. Since green has always been a color in prime demand, it’s surprising that this variety of corundum never caught on. Apparently, some clever marketers agreed. In 1984, a company staged a marketing campaign to promote green sapphire. Full-page ads appeared monthly in major trade publications.

Their campaign might have worked, except that their asking prices were double and triple the current selling price of green sapphires on the open market. The campaign was short-lived. The two-level system of pricing remained for less than two years. When the advertising stopped, everyone agreed that green sapphire wasn’t marketable at the higher prices. Today, green sapphire prices are affordable at $60 per carat for a fine-quality stone.

Jade cannot be overlooked in a discussion of green gems; green is the most prized jade color. Perhaps the reluctance that dealers show toward jade stems from their fear of not knowing the true value, and indeed, jade is hard to evaluate. Even with years of experience, one can falter. Value is based on color, translucency, polish, finish, and uniformity of color, texture, size, and shape.

Of great concern is the use of dyes and the existence of many jade imitations. “B” jade, which has received much publicity in the past few years, has had a powerful acid bleaching treatment to eliminate brown or black stains, followed by a polymer impregnation. The best test to identify “B” jade uses infrared spectroscopy. Buy jade from a reputable source that practices full and ethical disclosure.

Dealers usually sell jade by the piece, not by carat weight. For an untreated green jade cabochon in an 8×10 mm size, expect to pay about $1,000 for fine quality. Lower-quality green jade can be less than $100. The top specimens can easily exceed $5,000 for an 8×10 mm and $25,000 or more for larger stones.

Green zoisite, although rare, can be a green option for collectors. This gem has been marketed only for the past half-dozen years or so. During mining for the brownish variety of zoisite that heat-treats to the blue and purple varieties known as tanzanite, some natural green stones were found. The supply is so limited that it will remain in the hands of just a few collectors. The price is $1,000 per carat or more for a stone of fine quality.

The least expensive green offering is green quartz. This variety of quartz is obtained by irradiation. Prices for these gems are only a few dollars per carat. Perhaps its popularity in the industry will compare to that of blue topaz.

The treatment issue. In Brazil, Opticon has become the preferred enhancement for emeralds, but the trade isn’t completely satisfied with it. Opticon may discolor within a few months to a few years. The Arthur Groom Gematrat treatment is a similar resin but is more stable without discoloration, according to the New York company. These claims are being studied.

Some dealers still prefer cedarwood oil, but the oil’s composition has changed over the years. There are many oils used and many resin formulas. The varying durability and stability of these products and the difficulty in identifying them have left dealers and consumers in a predicament.

At the World Emerald Congress in Bogota, Colombia, last February, dealers debated emerald enhancement issues. It was proposed that laboratories disclose the level of enhancement, such as slight or heavy. Some labs are adopting this or similar terminology.

Media stories about treatments have hurt the prices of emeralds. Consumers don’t like what they’re hearing, so they’re shopping for green alternatives. Josh Hall of Pala International says that since the emerald problems began surfacing his company is selling more tsavorite, chrome tourmaline, chrome diopside, and demantoid garnets. At present, none of these green alternatives is enhanced in any way.

Beware the green impostors. This year in Tucson, one dealer was exhibiting “diffusion-treated” green topaz. The material was reportedly Nigerian white topaz that had been treated to a medium dark bluish green color. Prices were only $2.50 per carat, but beware of this material being passed off as something other than what it is.

Green synthetic spinel and green glass are two imitations that should cause no identification problems. The refractive index and single refraction are easily tested with standard gemological equipment.

There are a host of synthetic emeralds. In recent years, the hydrothermal method has been most popular and has dramatically reduced the prices of synthetic emeralds. Hydrothermal emeralds in all sizes can be found for $75 per carat. A flux grown product can be found for about $130 to $140 per carat.

Richard B. Drucker is the president of Gemworld International and publisher of The Guide, a pricing periodical he began in 1982. An international gemstone consultant, he has published numerous books on the jewelry industry.