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Brazilian Emerald

Written by Modern Jeweler On May 2, 2013.

Late in the 1970s, when ads hawking emeralds for $5 apiece started appearing nationwide, gem dealers weren’t sure if these dull, opaque stones with their mottled, dusty sage-brush color should be called “emerald” or “beryl,” emerald’s family name.

Now, long after the $5 emerald campaign has joined the annals of schlock, experts begrudgingly call these stones “emerald” because they contain chromium, a greening agent that renders beryls emerald. This gemological verdict didn’t improve the standing of the source of these fish-tank stories: Brazil.

Ever since Brazil became the breadbasket for affordable emerald in the early 1960s (emerald was first discovered there around 1920), the country’s major mines, for two decades located exclusively in the northeastern coastal state of Bahia, had been saddled with a reputation for lackluster quality. Even today, many dealers liken the importance of emerald-rich Brazil to that of sapphire-rich Australia whose blackish stones were, until recently, a staple of low-end jewelry.

Today, however, Brazil has radically upgraded its image as an emerald mining center. Finds made since 1980 at Itabera in Minais Gerais, Santa Teresinha in Goias, and Nova Era near Itabera are supplying the best emerald Brazil has ever produced. Indeed, top stones from these mines beg comparison to Colombian emerald-the highest accolade this species can earn.

The emerald world as we know it today emerged in the late 1970s and is composed of three mining powers: Brazil, Colombia and Zambia. Until very recently each country played a fairly static role in terms of market preference. Colombia dominated the high end, Zambia occupied its middle and Brazil was left with the bottom. While this pecking order is still pretty much intact, Zambian and Brazilian goods have won enough trade admiration to seriously challenge the status quo.

The upheaval began in Israel around 1977 when colored stone dealers in Tel Aviv set out to make a market in a recently discovered variety of African emerald from Zambia whose stark, bluish green at first offended purists.

To cultivate higher regard for this material, the Israeli cutters who made a commitment to craeting a market for this gem simply skirted the color issue altogether. Their shrewd end-run maneuver consisted of two parts. First, they cut stones to emphasize their glassy brilliance and above-average (for emerald, that is) clarity-a tactic especially endearing to America where the all-pervasive 4C’s diamond aesthetic had given cleanliness parity with, and sometimes an edge over, color. Second, the Israelis offered calibrated stones in a wide variety of fancy shapes, a boon to mass-producers of jewelry.

As a result, U.S. and then European resistance to Zambian emerald, based solely on color, melted. Yet Japan, the main pillar of the fine emerald market, has never budged from its fierce loyalty to Colombian goods.

Because this loyalty is based primarily on color, “the Japanese have warmed to Brazilian goods ever since new strikes there brought pleasing-color goods into the market,” explains an emerald dealer who sells to both markets. By “pleasing color,” he means stones which bear closer resemblance to Colombian goods than Zambian.

Until the finds in Itabera, Santa Tereshinha, Socoto, and Nova Era, the norm for Brazilian emerald was the lifeless, one-dimensional material, typical of Bahia, that was usually tinged with gray or brown and so filled with black spots that dealers used the diamond term “pique” to describe them. However, Bahia still meets the need for low-end emerald. Millions of carats of Bahia rough are cut yearly in India.

Livelier, purer green goods from Itabera allowed Brazilian emerald to transcend the ranks of promotional and loss-leader jewelry. But the new mines are contending with Colombian and Zambian stones in the middle of the mainstream market.

Brazilian Aquamarine

Written by Modern Jeweler On May 2, 2013.

In the past twenty years, aquamarine, the treasure of mermaids beloved for thousands of years, just hasn’t been getting much respect.

Jewelry manufacturers in the United States have developed the habit of jilting this blue beryl in favor of an overly abundant and less expensive look-alike: blue topaz. “It’s a matter of economics,” explains one gem cutter. Per-carat prices to jewelry manufacturers for bulk aqua are at least 10 times what they are for bulk blue topaz.

Elsewhere in the world, however, near-giveaway prices for blue topaz have not shaken loyalty to aqua. If anything, they have strengthened allegiance to it. “In America, manufacturers want color, they want look,” a dealer says. “But abroad they want lasting value.”

By lasting value he means long-term appreciation. That’s something blue topaz, which owes its blue color to relatively recently developed treatment techniques, can’t boast. The history of blue topaz makes it the gem equivalent of the LCD watch, a technological marvel that once commanded hundreds of dollars and is readily available today for less than $5.

But in recent years, the situation is changing. Jewelry designers looking for pastel gems to set in platinum and white gold decided that the color of blue topaz was too harsh for these metal’s subtle luster: more at home in sterling silver than premium metals. So aquamarine started a comeback of sorts. Its beryl brilliance looks at home in pricey platinum. And its subtle cool appeal is right for millennial minimalism.

Despite the change of heart with regard to fine aqua, it is doubtful the supply situation for fine stones will improve. First of all, production of fine aqua is spotty. Fine stones are eye-clean, a necessity with pastel-color gems, and have robust shades of blue that are a far cry from the anemic aqua hues one sees in inexpensive jewelry. “With most stones so pale, it’s no mystery why blue topaz has caught on so,” a Brazilian gem expert says.

Nevertheless, there are some who think fine aqua is far too expensive relative to fine blue topaz. They assume that because Brazilian aqua is commonly heated, it should be as easy to produce fine aqua as it is irradiated blue topaz.

That’s just not so. For while deep-color blue topaz can be produced almost at will, deep-color aqua can’t and never has been. Heating is used to permanently remove common green overtones from stones, not deepen their color. Interestingly, similar green overtones in many African aquas cannot be removed by heating in ovens, a distinct advantage for the Brazilian variety. Yet even so, Brazil can’t produce enough fine aqua to meet world demand.

So Brazilian aquamarine prices seem poised for a comeback as connoisseurs rediscover its appeal.

Brazilian Alexandrite

Written by Modern Jeweler On May 2, 2013.

Gem connoisseurs still can’t forget the moment in 1987 when they first saw specimens from the spectacular find of alexandrite in Minais Gerais, Brazil’s province of gem plenty. “A dealer showed me a 400-piece parcel weighing 126 carats of which 35 stones were above a carat,” one Brazilan gem specialist recalls. “That was way more alexandrite than I had seen in the previous five years.”

But the parcel wasn’t just good news from a quantity standpoint. Its quality was equally impressive.

“The best of the stones were as good as, if not better than, any pieces I had ever seen,” he continues. “I understood at a glance why Brazil’s new alexandrite deposit was the find of the decade.”

Other dealers swaddle their first impressions of this color-change chrysoberyl in similar enthusiasm. It’s hard not to, once you see evidence that the supply of the world’s most glorified connoisseur gem has now doubled.

Alexandrite is a fairly modern gem, unknown before 1830, when it was found in Russia’s Ural Mountains. Since its two color states, green and red, were the same as the host country’s military colors, and since its year of discovery was that in which Czar Alexander II came of ruling age, the color-change chrysoberyl was named “alexandrite” as a tribute. That was a wise move for, in time, it became a very prized gem among Russia’s aristocracy.

But practically all of Russia’s alexandrite was mined during the nineteenth century. Just when the gem seemed headed for extinction, far larger deposits were found in Ceylon (now Sri Lanka), the island nation to the south of India. Later on, Brazil became still another contributor to world supply, although its stones didn’t command respect until the recent discovery.

Early in the twentieth century, alexandrite aesthetics were far more a matter of debate than they are today, with dealers tending to be evenly divided in partnership between Russian and Ceylonese stones. For example, gemology pioneer Max Bauer was unabashedly partial to the Ceylonese variety. In the last 50 years, however, the debate has become almost completely one-sided in favor of Russian material.

Very likely, the trade’s favoritism has a lot to do with the extreme rarity of Russian material, a key component of its value, although dealers have sworn to us that their preference was based purely on beauty. In any case, Russia is now to alexandrite what Burma is to ruby.

The excitement over the new Brazilian alexandrite is that the best of it rivals Russia’s best. Unfortunately, Brazilian alexandrite may also soon rival Russian material in rarity. The mine at Hematita, near Nova Era, produced a consistent supply of fine material for a few years but as the eighties ended, disputes over mining claims disrupted production. Since it has never resumed, the deposit may be exhausted. It may be that Hematita alexandrite will be the twentieth century’s version of Russian alexandrite: a bonanza that produces enough to create desire, but not enough to fufill it for most collectors. Fine alexandrite seems destined to be a gem sought on the secondary market, available only in estate and vintage jewelry.

Nobody knows how much material was mined at Hematita. Insider estimates range from 5,000 to 10,000 carats, a tiny amount for major gems like ruby or emerald but a staggering number for a gem as rare as alexandrite.

But as anyone who has seen the Hematita alexandrite knows, these stones challenge common experience with this species. Although famous for changing color from green in sunlight to red in incandescent light, few alexandrites actually make a full-fledged color change. Usually there is bleed-through from one color state to another or too much color impurity to start with to permit any significant change. Because total color-change alexandrites are so very seldom seen, the trade thinks it axiomatic that in this species, such a characteristic is a rarity.

Now Brazil has raised trade expectations considerably because Hematita alexandrite excels at 100 percent color change. “The completeness of the color change in most of the material is one of the most amazing things about it,” explains a dealer. “In Sri Lankan stones, there always seems to be an undertone of secondary brown or yellow.”

Furthermore, the Brazilian stones boast admirable color richness. Greens in smaller sizes tend to be yellowish while those in larger stones are bluish. As for the red, the gem buyer compares it to the violet color of rhodolite in smaller stones and that of rubellite in larger pieces. One very lovely 2.53-carat stone shown to us by a dealer in California turned from a deep green to a luscious raspberry red.

The other virtue that endears Hematita alexandrite to collectors is its better-than-usual clarity.

Boulder Opal

Written by Modern Jeweler On May 2, 2013.

During the 1980s,when the super-strong yen pushed black opal prices to levels beyond the reach of the rest of the world, far-less-expensive boulder opal came on strong in America as a substitute. Then, during the withering of world recession of the early nineties, when the Japanese also balked at the high cost of black opal, this alternative variety came on even stronger in Japan.

In both countries, there was no other choice-other than assembled stones such as opal doublets, or lab-growns such as Gilson opal. Detractors of boulder opal don’t care that this gem is the only all-natural option for those who want the look of black opal without the price. Says one, “Settling for boulder opal in place of black opal is like settling for caviar made from cod, instead of sturgeon, roe.”

Not! Boulder opal isn’t some form of low-grade black opal but a separate opal variety unto itself. Like the black opal it often resembles, it is found only in Australia. In fact, the first discovery and full-scale mining of Australian opal, in 1872 and 1878 respectively, involved boulder opal from Queensland, to this day the only producer. It wasn’t until 1903 that miners found black opal at Lightning Ridge in the next-door state of New South Wales. Eventually this magnificent opal became the world’s choicest and supplanted demand for the boulder variety.

Ninety years later few appreciate the role boulder opal played in first establishing Australia as the world’s chief opal source. Now that there’s a revival of interest in boulder opal, it might be worthwhile to see why the gem earned Australia quick renown more than a century ago.

Gems of the Outback

Boulder and black opal could be called wasteland wonders, since deposits of both are scattered throughout Australia’s vast stretches of semi-desert known as “outback.” Indeed, aridity is a precondition for creation of opal, as Peter Keller explains in his engrossing book, Gemstones and Their Origins.

Simply put, opal is a silica gel deposited as a filling in rock fractures by seepage of seasonal rains into the ground. During the long dry spells that follow these rains, the gel hardens by evaporation of most but not all of the water content. Because this gel is composed of countless tiny stacked spheres, it diffracts light into distinctive prismatic color patters-provided these silica spheres are the same size and arranged in orderly rows. The more precise the arrangement of these light-diffracting spheres, the better the color play. Of course, colors sand out better still when the host rock in which opal forms is dark rather than light.

It is here that boulder opal differs significantly from black opal. Found in boulders of charcoal-brown, iron-rich sandstone called “ironstone,” it is the only precious opal cut with host rock (known as “matrix”) as a backing. Although black opal is sometimes thought to be cut with matrix, this backing is, in fact, colorless opal called “potch.”

Because boulder opal forms in thin films reminiscent of the tops of opal doublets, many a novice mistakes them for such. (Doublets are made by fusing opal slivers to a black base of glass, onyx and other materials with cement that bubbles when touched with a hot point.) Indeed, for years boulder opal was sold as “nature’s doublet.”

The fact that boulder opal is never more than a thin layer on thick matrix works for more than against this gem. First, it does not graze and has superb durability. And, second, while it isn’t as a rule cut into cabochon or calibrated sizes (ruling out use in mass production jewelry), boulder opal lends itself to free-form shapes that are ideal for custom jewelry.

Boulder Aesthetics

Because boulder opal is mostly ironstone matrix, it is priced by the piece rather than the carat. When selecting boulder opal, dealers advise jewelers to evaluate pieces on the basis of three critera.Ideally, stones should face up with a continuous sheet of opal. However, since such stones are exceedingly rare, collectors will sometimes allow for a tiny trace or two of surface ironstone-but only if it contributes to, not detracts from, its beauty.

Next, the stone should have intense color-the result of the hue-heightening contrast between its translucent face and its dark-brown background. As a general rule, the thinner the band of opal on the matrix, the richer the color. So while the opal layer should be more than a veneer, thickness past a certain point can be a drawback.

Last, color patterns should be broad, even, and definite. Although boulder opals often have rich multi-colored combinations of red, yellow, blue and green, stones more commonly feature blue and green exclusively. At their best, these latter stones have large swirls of flashing color that many liken to an earthscape as seen from space.

Blue Topaz

Written by Modern Jeweler On May 2, 2013.

Blue topaz is the most affordable gemstone, giving consumers the look of aquamarine for less.

But it doesn’t start out its life that beautiful blue. When it comes out of the ground, it is colorless. The color of blue topaz is an achievement of the gem treater’s art. In the 1970s, dealers discovered that they could treat white topaz by exposing it to radiation, and then heat. What was originally a colorless gem then turned the blue of aquamarine.

When blue topaz first appeared on the market, it was a pricey novelty. But as more dealers figured out how to produce the color, production exploded and prices dropped to their affordable levels today.

The blue color is permanent, making this gem ideal for affordable gemstone jewelry.
Quickly after the new color treatment was developed, blue topaz became a very popular gem with consumers.

But despite the success of blue topaz, many jewelers who sell it do so with ambivalence.
Granted, they admit, the stone has unrivalled beauty for the money. But the fact that the color is created by man makes blue topaz feel less natural than other gems. Gems like sapphire may also have their color improved by heat. But the enhancement of sapphire doesn’t always work, and it is a difficult and expensive process. In contrast, blue topaz is easily and affordably mass produced.

Trade ambivalence about topaz is evident in the marketing and merchandising of the gem. Few retailers even bother to tell consumers that blue topaz owes its color to either a nuclear reactor or a linear accelerator.

Some see such non-disclosure as a reaction to fears about irradiation. But now that many products, including food, are commercially irradiated, that is becoming less of a taboo. Interviews with treaters, dealers and government officials lead us to conclude that blue topaz poses no danger. First of all, stones treated in ways that leave residual radiation are quarantined (usually anywhere from three months to one year) until levels read ultra-conservatively low. By the time these stones get to jewelry stores, radioactivity is unmeasurable with conventional Geiger counters. What’s more, even when the Nuclear Regulatory Commission (NRC), which licenses reactors in the United States where most topaz is treated, ran radioactivity tests of irradiated blue topaz using ultra-expensive and sensitive measuring devices, it found no cause for concern.

So why neglect to tell the public about irradiation? The answer, we think, lies in the fact that blue topaz is a high-tech hybrid that transcends all conventional classifications. On one hand, the stone is natural, starting life as super-abundant colorless or ever-so-slightly tinted topaz from places like Brazil and Sri Lanka. On the other hand, its color is entirely manmade.

The names for topaz colors are actually dealer shorthand for the different processes used to produce them. The final resulting color depends on the process and the trace elements present in the original material. Dealers match the origin of the original material with process to achieve the desired results. The most popular process is Sky blue topaz, which is irradiated in a linear accelerator, usually a commercial irradiation facility in California. Topaz irradiated with electrons is generally light blue in color, similar to aquamarine. London blue topaz, in contrast, is produced by neutron irradiation in a nuclear reactor. This topaz may be much darker in color, more like a tourmaline blue.

If the neutron irradiation technique is used, stones fall under NRC jurisdiction. Current NRC rules require that neutron bombardment done in the United States, regardless of gem species, be performed only by NRC- licensed reactors, which must subject the stones to a battery of tests before releasing them. If stones are reactor-treated in other countries, their U.S. importers must be licensed by the NRC to import them. In Europe, release standards not quite as strict and testing is handled by individual reators before release.

However, blue topaz irradiated in a linear accelerator is not subject to regulation either in the U.S. or Europe because it doesn’t have noticeable residual radiation.

Perhaps blue topaz will someday be celebrated as union of nature and science rather than being devalued for that fact. This gem is a product of a venerable tradition of improving on nature that began long ago with the alchemists.


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