Should We Measure EMERALD TREATMENT BY DEGREES?
The contentious issue of how to deal with emerald treatment prompted some innovative proposals at the first World Emerald Congress held in Bogota, Colombia, in February.
One of the most interesting came from Ron Ringsrud of California’s Constellation Gems, who suggested that trade labs should recognize and identify four levels of treatment – negligible, slight, medium and heavy, depending on the amount of filler used. He said that more than 40% of the emeralds he sees have only a negligible amount of treatment.
Other suggestions included asking Merck & Co. Inc. – a U.S. chemical company that produces most of the cedarwood oil used in treating emeralds – to develop a new version of the oil that would be more compatible with jewelry industry needs. The need for a change arises, attendees at the congress learned, because Merck over the past decade has changed the formula for its cedarwood oil to meet the needs of the microscopy industry. This change in viscosity makes the oil only a temporary enhancer for emeralds, an unacceptable situation for emerald dealers.
Tom Chatham of Chatham Created Gemstones suggested another treatment possibility: filling emerald fissures with synthetic emerald.
Mary Johnson from GIA’s Gem Identification Laboratory raised more questions than she answered by reporting that preliminary results of GIA research suggest enhancements with refractive indices closer to that of emerald work better than cedarwood. She declined, however, to reveal what they might be. GIA’s function is to research an issue, she explained, not determine if one product is better than another.
The idea of having four “grades” of treatment drew a quick and positive response. Dr. Henry Hanni of the Swiss Gemological Laboratory said his lab would adopt the system. Robert Kane of the Gubelin Lab, another Swiss venture, said his lab would follow up the idea and Ken Scarrett, head of the new American Gem Trade Association lab in New York City, said he’s ready and willing to study the proposal. “It appears to be what the industry wants,” he said.
Jaime Rotlewiçz, a Colombian emerald dealer, said he has talked to Merck about changing its cedarwood oil formula to meet jewelry needs. Meantime, he proposed that the oil be used as the most suitable filler until something better is produced.
A workable solution to the enhancement issue is urgently needed. Many dealers blame the use of two synthetic resins, Opticon and Palm oil, for falling emerald prices over the past few years. Opticon, a synthetic epoxy resin, has been found to change color over time and under ultraviolet light (found in sunlight). Palm oil, a name once applied (20 or so years ago) to a natural product, now refers to a synthetic epoxy resin product. It, too, changes color, turning white after only a few years. Gematrat, an enhancement developed by Arthur Groom of New York and Bogota, has dodged heavy criticism because it reportedly does not change color and is relatively permanent.
A rose by any other name. Dealers at the congress complained about how gem labs describe emerald fillers as much as they criticized the fillers themselves. They said the labs’ wording on identification reports makes it hard to promote the gem. Many Colombians and international dealers alike said words like “treated,” “fracture filled” and “Opticon-type” have killed the sale of emeralds that needed to be enhanced. Increasingly used during the congress were terms such as “enhanced,” “fissures” and “medium.” But don’t expect any fast response from the labs. Most take weeks or even months to update their nomenclature – should they choose to do so.
The Swiss Gem Lab’s Hanni suggested the Colombians set up their own identification laboratory in Bogota. Then they could say what they want on a certificate.
One problem with enhancements is that every emerald is different. Emeralds from Cosquez fill differently than do those from Muzo or Chivor. Refractive indices of stones from each mine differ slightly, depending upon the amounts of chromium and vanadium present. And fissures in gems from one mine site may be deeper, wider or longer than those in material from others. These variations suggest that there’s need for a number of similar yet slightly different media, depending on the actual source and deposit.
The Bogota congress produced a lot of worthwhile talk. It remains to be seen how much of that talk will be converted into action. – Gary Roskin
For more information about the Bogota congress, see the feature on emerald supply starting on page 100. A report on emerald as May’s birthstone appears on page 46.
FRED WARD SEEKS MISSING JEWELER
Fred Ward, owner of Blue Planet Gems in Bethesda, Md., is trying to find a way to overturn last year’s court ruling in a celebrated fracture-filled emerald case. He’s offering a $2,500 reward for any information that will identify the jeweler who soldered sizing beads in the shank of the now infamous emerald ring.
Ward hopes that jeweler might provide new information that could prove that Ward was not responsible for filling the emerald in question. He believes that this unknown second jeweler worked on the ring between May 10 and Aug. 28, 1994, during which time the emerald was filled with resin and oil.
Testimony from the jeweler could provide the courts with enough information to throw out the case, says Ward, but the information is needed by June 15 for a legal appeal. He adds that the person or persons who did the soldering and filling did nothing illegal and are not involved in the lawsuit.
Ward has asked a number of trade publications and members of the trade to accept phone calls from anyone with information about the unknown jeweler. Anyone with information that could lead to the identification of the jeweler who did this repair work on the emerald ring should contact Gary Roskin, JCK Gemstone Editor, at (610) 964-4270. All calls will be kept strictly confidential.
A MARVELOUS TRIBUTE TO COLORED DIAMONDS
One of the most anticipated reference books on fancy colored diamonds was recently released.Collecting and Classifying Coloured Diamonds, An Illustrated Study of the Aurora Collection is the culmination of an eight-year investigation by Stephen Hofer, a leading authority on colored diamonds. With the help of Nick Hale, a noted color science expert, Hofer details the Aurora Collection, one of the finest collections of colored diamonds in the world.
The collection has been on display at the American Museum of Natural History in New York City since 1989. It’s included in the museum’s highly acclaimed “Nature of Diamonds” exhibit, which has drawn more than a quarter million visitors and has been extended through Aug. 30, 1998.
To illustrate his work, Hofer chose Tino Hamid, an award-winning photographer. Hamid has been photographing gems for more than two decades and shows his expertise in duplicating the collection’s actual color.
Collecting and Classifying Coloured Diamonds is laid out in 12 chapters featuring easy-to-read text along with more than 700 color photographs and 650 illustrations. For example, chapter nine classifies more than 275 diamond colors and chapter 12 lists more than 1,400 colored diamonds that have appeared in public auctions. Last but not least is a complete bibliography of references that were used to establish the authenticity of the study. Hofer hopes that this work will become an important reference tool for jewelers, gem dealers, clients and collectors.
Hofer began his career in 1976 working as a geophysicist at the University of Connecticut, then entered the gem and jewelry industry in 1979 when he became Dr. Vincent Manson’s research assistant in GIA’s research laboratory. Hofer is a Graduate Gemologist (G.G.), a Fellow of the Gemmological Association of Great Britain (FGA) and an accomplished colored diamond cutter. He’s a graduate of the American Institute of Diamond Cutting (AIDC). In 1985, he became president of Colored Diamond Laboratory Services and currently operates a consulting service to the trade.
Collecting and Classifying Coloured Diamonds is available through Ashland Press, 589 Fifth Ave., New York, N.Y. 10017; (800) 451-2558. Price is $300.
Tel Aviv to Host Rough Diamond Conference
The Israeli diamond industry will hold “Israel’s Tribute to the Rough Producers: An International Conference on Rough Diamonds,” June 23-24. The event is being organized under the joint auspices of the Israeli government, the Israel Diamond Manufacturers Association, the Israel Diamond Exchange and the Israel Diamond Institute. Moishe Schnitzer is chairman of the conference organizing committee.
The conference will be preceded by the opening of a rough diamond trading floor in the Israeli bourse. Itzhak Forem, president of the Israel Diamond Exchange, notes that Israel has consumed some $75 billion worth of rough in the last 60 years.
Schnitzer claims there never have been so many high-level rough producers and consumers scheduled to attend such an event. “For the first time,” he says, “the Israeli diamond industry will be able to greet all of the rough diamond producers who represent the first step in the diamond pipeline.”
Executive directors and chairmen from major producing companies such as De Beers, ARS (Russia), Ashton (Australia), Endiama (Angola) and Rio-Tinto (Australia and, in the future, Canada) will discuss current and future rough production. South African producer Trans Hex will touch on the role of small independent producers. Anthony Oppenheimer, president of De Beers’ Central Selling Organisation, will offer a keynote address, while CSO Directors Tim Capon and Steven Lussier also will speak.
Peter Goss, director of the International Diamond Division of ABN-AMRO, will discuss “Financial and Risk Management in the Diamond Trade.” The bank has more than $1.8 billion in credit exposure to the business. Israeli industry, banking and government officials will brief attendees on the state of the country’s diamond industry.
MAY’S BIRTHSTONE: EMERALD
Emerald, known for its rich green color, has been around for thousands of years. It’s been treasured for its beauty since its first discovery in the mines of Cleopatra in upper Egypt, not far from the coast of the Red Sea. It reached a still wider audience when the 16th century Spaniards came upon, and appropriated, the native Colombian mines of Muzo and Chivor. Emerald is considered the number one green gemstone, one of the “big three” of colored gems – emerald, ruby and sapphire.
Emerald’s vivid saturated green has given it its place in the gem world, and its long history has kept it there. For those born in the month of May, this is their birthstone.
Locality. This precious gemstone is found in quite a few countries, with Egypt the first and Colombia acknowledged as the source of the most and the finest. There also are fine quality deposits in Zambia (with 15% of world production), Brazil (10%), Russia (5%), Madagascar (3%), Zimbabwe (2%) and Pakistan, Austria and Tanzania. But none of these sources produce emeralds as spectacular as those from the mountainous mines of Colombia, which account for 60% of total world supply.
As the crow flies, Colombia’s emerald fields lie more than 100 miles outside the capital city of Bogota in the three mountain ranges of the Andes. Muzo and Cosquez are located relatively close to each other on the slopes of the Western range, along with the smaller mines of Penas Blancas, Calceteros, Chizo-Cuepar and Cerro La Chapa. Chivor and the smaller mining area of Gachala lie on the slopes of the Eastern range.
Whether in Colombia or elsewhere, each mine has its own unique occurrence and yields emeralds with their own unique appearance and identifying features. Colombian emeralds, for example, contain a classic three-phase inclusion – of a liquid, a solid and a gas – in jagged pockets of crystal lattice. Many of these gems are colored by chromium (showing an identifiable, visible light spectrum) and contain small fissures created by the strain of the chromium content. Brazilian emeralds contain a two-phase inclusion – a liquid and a gas – with a somewhat squarish “blocky” appearance. These gems generally are much lighter in color (less chromium) than the Colombian stones, showing fewer fissures as the color becomes less saturated. Zambian material has even less chromium (and fissures) but shows a very saturated green, due in most part to the coloring agent vanadium.
Gemological properties. Color: The top color for emeralds is either vivid green or vivid bluish green. Vivid yellowish green comes in third, with lower saturations ranking further down the list. Of course, emerald is known for its saturated color. But tone plays an important part in its beauty (tone ranks from very light to very dark). The tone of emeralds is medium-light to very dark. Gems that are too light in color are classified as green beryl.
Clarities: The clarity of an emerald is considered less important than its color. Because of the nature of their structure, most emeralds have numerous fissures and eye-visible inclusions. That’s why emeralds for centuries have been enhanced with oils to reduce the appearance of blemishes. (See “Should we measure emerald treatment by degrees?” on page 40.)
Refractive index: The RI of emeralds varies with locality and with laboratory processes. Ranges of the natural gem are 1.577 to 1.583 +/- .017. Most synthetics have lower ranges and birefringence.
Fluorescence: Reaction to ultraviolet light can vary depending on the amount of chromium and iron present in the gem.
Gemologists examine these four identifying features to determine whether an emerald is natural or synthetic. Because each of these properties can vary, even if only slightly, all four tests often must be performed to give the gemologist a true result.
Enhancements. Various oils and resins are used to mask the fissures of emeralds, but the features that identify these enhancements are similar in appearance. Locating fissures can be a two-part process. First, if you look at the surface of the gem using overhead reflected light, you’ll see fissures as a darker gray line running in directions other than the straight polish marks. If you use darkfield illumination in a microscope, you’ll see how deep the fissure is and the liquid inside. If the enhancement’s RI is close to that of the emerald, then a flash of color might be seen coming from the enhancement. Typically you will see yellow or blue flashes of color.
Imitations and synthetics. If imitation is the sincerest form of flattery, than emerald definitely has been flattered. Glass, plastic, colorless beryl triplets, emerald and beryl doublets and other green gems all have been used as emerald look-alikes. Magnification is the first key for identification. Look for gas bubbles, cement planes in doublets and triplets, and natural and synthetic inclusions that normally should not be there.
Today it’s not as easy to identify an emerald or emerald substitute as it was 40 years ago. Back then, you could use a Chelsea filter to separate emerald from other imitations. But today, with the proliferation of very good synthetic emeralds, a simple test like the Chelsea filter just will not work.
Like many gemstones, emerald has been produced in a laboratory. Carol Chatham was the first to successfully produce the flux-grown emerald. These are produced on a grand scale now under close supervision of his two sons. Other synthetic emeralds on the market are produced by both flux and hydrothermal processes.
Identification of synthetics can be difficult at times, since portions of the synthetic growth processes are very similar to the natural. Many of the gemological properties are the same in both, so gem-testing equipment is a must. A microscope can be helpful if you’re examining typical inclusions. If there is no obvious natural or synthetic inclusion, magnification will not be the ultimate determining factor.
Values. Fine quality emeralds in decent sizes can be affordable. One- and two-carat stones, with slight to moderate inclusions and medium dark vivid green or bluish green color, can command $2,000 to $4,000 per carat. Emerald shapes are the most appropriate for the shape of the rough crystal, but other shapes are available as well. It may seem curious, but the round is one of the least available shapes for an emerald.
Astrological signs. It’s possible that someone born in May might not like emerald as a birthstone. You might assume that, astrologically, diamond is an alternative, but this is not so. Sapphire is the stone for the period from April 21 through May 20, and it’s followed by agate from May 21 to June 20. While not one of the transparent gems of the traditional list, there are many agates – picture, moss, dendritic lace and others. They lend themselves extremely well to jewelry art.
– by Senior Editor Gary Roskin, G.G., F.G.A.
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 authorityJohn 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.