The Discovery of Paraíba Tourmaline

In 1989, exceptionally brightly colored tourmalines were discovered in the state of Paraíba, Brazil. Researchers determined that these elbaite tourmalines received their intense coloration from copper. (The stones also contained manganese and often a bit of bismuth). These stones generated great excitement, and their prices soon exceeded $20K per carat. For paraíbas, color is more important than clarity. Eye-visible inclusions are easily tolerated and only make slight value differences.

Soon after the original discovery, similar tourmalines were found in Brazil’s Rio Grande Do Norte state, just north of Paraíba state.

Nigeria

In 2000, more tourmalines also colored by copper were discovered in Nigeria. Generally, the Nigerian gemstones didn’t have the same vivid saturation as the Brazilian material. However, the range of colors did overlap.

Mozambique

A few years later, still more copper-bearing tourmalines were discovered, this time in Mozambique. They also had colors similar to the Brazilian material.

Liddicoatite Paraíbas

In 2010, the Gübelin Gem Lab analyzed faceted cuprian-bearing liddicoatite tourmalines, possibly from Mozambique, with colors and concentrations of copper and manganese like elbaite paraíbas. In 2017, the Gemological Institute of America (GIA) analyzed similar specimens. These gemstones have appeared in gem markets. However, like most tourmalines, cut paraíbas belong predominantly to the elbaite species.

Identifying Paraíba Tourmalines

Paraíbas are elbaite tourmalines colored by copper (except, of course, liddicoatite specimens). They have a refractive index (RI) of 1.603 to 1.655 and specific gravity (SG) of 2.84 to 3.10. They have a high birefringence of 0.013 to 0.024, so you’ll almost always see doubling with your loupe. (See the main tourmaline gem listing for the properties of liddicoatites).

Paraíba colors are mostly green to blue. However, Mozambique has produced some pinks and purples. The main color criterion, however, is the saturation level, from 4, “Moderately Strong,” to 6, “Vivid.” Tones range from medium light to medium dark.

Chrome tourmalines are the only other tourmalines that approach a comparable saturation level (5). However, these gems have a higher RI, 1.772 to 1.778, and a much lower birefringence, 0.006. So, if you find an elbaite tourmaline with a saturation level of 5 or higher, you most likely have a paraíba.

On the other hand, if you have an elbaite with paraíba colors but a saturation of 4, you have to prove that it has copper content. A spectroscope reading will distinguish some of these gems. The key feature is a broad area of general absorption starting at 600 nm, present only in copper-bearing gems. However, a standard spectroscope will only distinguish stones with the highest copper content. Send the others to a major gem lab for testing.

Enhancements

Paraíbas may receive heat treatment. This will lighten stones with darker tones and change violet and purple colors into blues.

Although clarity doesn’t play a major role in paraíba value, these gems may still receive clarity treatments. For example, lasers can remove dark inclusions, and fillers may decrease the visibility of surface fractures. However, stones with evidence of clarity treatments will hold less value than untreated gems of similar qualities. As a result, paraíbas don’t receive these treatments very often.

Care

Avoid cleaning paraíba tourmalines with ultrasonic or steam devices. Vibrations and heat may cause liquid inclusions to expand, shattering the stone. Instead, use a soft brush, mild detergent, and warm water.

From Gem Society

You all know the saturated blueish-green to green variety of beryl well—it’s emerald, of course.

You definitely also know the green-blue to blue beryl we call aquamarine and, most likely, its pink to orange-pink cousin, morganite.

But what about the red variety of the mineral? It’s a rare one so it doesn’t have a lot of exposure, but gem connoisseurs love it.

Red beryl is a one-source gemstone that is extremely rare.

The Utah Geological Survey estimates that for every 150,000 gem-quality diamonds unearthed, one crystal of red beryl is found.

The gemstone gets its rich color from trace amounts of manganese and is a 7.5-8 on the Mohs hardness scale.

Red beryl is also known as bixbite after its discoverer, mineralogist Maynard Bixby, but that label has been discredited by various gem experts and trade associations, like CIBJO, because it’s easily confused with another mineral named after the same man—bixbyite.

Here are five things to know about this gorgeous red gemstone.

1. Gem-quality material comes from only one place.

Bixby found this member of the beryl family more than a century ago, in 1904, at his claim in the Thomas Range in Utah.

According to the Gemmological Association of Great Britain, after Bixby’s early discovery, prospector Lamar Hodges found a second deposit of red beryl at what came to be known as the “Ruby Violet” mine in the Wah Wah Mountains of Utah.

Wah Wah is the only locality in the world known to have produced gem-quality red beryl. According to an article from the Gemological Institute of America, as of 2003 only about 60,000 carats had been mined.

Red beryl has been found at a few other locations in the United States as well as Mexico, but at these locations, the crystals are generally too small, short or imperfect to facet.

Currently, there is no commercial production of gem-quality red beryl, according to several sources.

2. Not surprisingly, big sizes and fine quality stones are hard to find.

This can be said for many colored gemstones, especially when you reach the higher-quality tiers.

But according to specialists, a 2-carat red beryl is considered as rare as a 40-carat diamond, and the largest known faceted red beryl is 8 carats.

Resource website Geology.com says the largest red beryl crystals found at the Ruby Violet claim are about 2 cm wide and 5 cm long but added that most gem-quality crystals are under 1 cm long and most faceted beryl stones are 0.25 carats or less.

The average size is around 0.08 carats, Monte Zajicek said. A 0.40-carat stone is large, and 1 carat is “exceptional,” he added… Most gemstones are 1 to 4 mm and “anything larger is a treat.”

In addition to being small, there’s a good amount of red beryl production not of gem quality.

According to GIA, only about 10 percent of the goods coming from Wah Wah were of a quality that could be faceted, while gemstone and mineral seller Hunter estimated the amount of gem-quality material is below 5 percent, even with taking into account stones that have been clarity-enhanced to become gem quality.

All of this is to say: Red beryl is the rarest of the beryl family and one of the rarest gemstones overall.

Luckily, most pieces of red beryl from the Ruby Violet area have a rich, saturated red hue, providing a great pop of color even when it’s only melee.

3. There’s always a market for red beryl, faceted or otherwise.

High demand for red beryl stems from several factors, the first being its rarity.

According to Zajicek, the gemstone is also benefiting from a demand for American-mined goods. But, he also noted, most demand for red beryl is coming from Japan, with a growing demand from Asian countries overall.

Added demand has increased “a decent amount” over the last four to six years as old collections recirculate on the market.

“As the public becomes more aware of this mineral, the need to have a piece in their collection goes through the roof,” He, too, noted a rising demand from the Asian market interested in the gemstone’s intense red color but added that some U.S. collectors—especially those from Utah—“are doing their best to keep some of it here … as they feel an extra attraction to the stone for being from their home state.”

There’s also a strong demand from mineral collectors, attracted not only to the color but also the hexagonal crystal shape of a well-formed rough red beryl.

4. Fine pieces go for top dollar.

Red beryl is rare and beautiful, and its prices can really show it.

Color-matched melee with a strong red hue can sell for more than $1,000 per carat, Geology.com reported, while “nice” gems weighing more than 1 carat—very rare, as noted before—cost several thousand dollars per carat.

5. There are some who prefer another name for this gemstone.

Besides red beryl and bixbite, there’s a third name for the material that’s preferred by some: red emerald.

Those against the use of the term argue that “emerald” refers to saturated green beryl only and worry it deceives consumers. In its article about red beryl, Gem-A said the term should be “decried” by gemologists, and Geology.com called it a misnomer.

Some companies are in support of calling it red emerald for a few very specific reasons, with the first being that red beryl has more in common with emeralds than it does with other gem beryl varieties.

Faceted aquamarine and morganite, for example, often are eye-clean. Green emeralds and red beryl, by comparison, often have inclusions, falling under GIA Clarity Grade Type III.

Additionally, unlike the lighter-colored beryl, emeralds and red beryl routinely have surface-reaching fissures, which affect color by altering the path of light through the stone but also provide places for grease or water to hide and can mean a risk for damage.

This means both beryl types—emerald green and red—are often clarity enhanced.

In a 1999 article that appeared in Professional Jeweller, gem expert Mary Johnson listed other similarities between red beryl and emeralds, including formation similarities, color zoning patterns, faceting considerations and more, such that “a color-blind gemologist … would not be able to easily tell the two varieties apart without a spectroscope.”

Antoinette Matlins, author and gemologist consultant, also wrote a piece, noting the similar crystallization patterns shared between the two.

She argued that ultimately, “there is really only one name that associates the gemstone to its mineralogical family, beryl, and quickly and accurately communicates its rarity as well as its color: red emerald.

“This is the one name that makes it clear the red variety has comparable rarity—actually, even greater rarity—and comparable, or higher value, as has been demonstrated at recent top-tier gem and mineral shows.”

In the most recent update to its Jewelry Guides in 2018, the Federal Trade Commission added a section about gemstone varietal names and sought comment from experts before finalizing.

The American Gem Trade Association submitted a letter to the FTC, noting that while it agrees with avoiding deception through misidentification of gem varietals, it found the use of “red beryl/emerald” or “red emerald/beryl” in presenting or selling was not deceptive for many of the same reasons outlined above, provided a full explanation be included as well.

Ultimately, the final draft of the Jewelry Guides advises marketers “not to use incorrect varietal names,” giving examples like using “yellow emerald” to describe heliodor or “green amethyst” for prasiolite.

Though the guides don’t mention “red emerald” directly, the Jewelers Vigilance Committee suggests companies selling the product not use the phrase.

]]> https://hubertjewelry.com/10-of-the-worlds-rarest-gemstones/ Mon, 24 Feb 2020 19:06:17 +0000 https://www.hubertgem.com/?p=2904 […]]]> There are roughly 200 varieties of natural gemstone known in the world today. Alongside the world’s precious gems (diamond, ruby, sapphire, and emerald) are numerous semi-precious stones, some of which are so incredibly rare that their value outstrips many of the world’s most valuable precious gems. Here are a few of the rarest from around the world.

1. TANZANITE // FOUND ONLY IN TANZANIA

Tanzanite is a beautiful blue variety of the mineral zoisite, and is so named because it is only found in a small area near the foot of Mount Kilimanjaro in Tanzania. The stone was not discovered in commercial quantities until the 1960s and since then its popularity has grown tremendously, thanks largely to the efforts of Tiffany & Co. Heat-treating tanzanite at very high temperatures can improve the blue coloration, so most gems on the market have been treated in this way, but any tanzanite that has not been heat-treated and has a strong blue color naturally will be of a much higher value. Because it is only found in one small location, the value of tanzanite looks likely to soar over time; once those mines have been emptied there will be no new stones coming onto the market—unless a new source is found.

2. BLACK OPAL // THE DARKER THE BETTER

Opals are usually a creamy-white color and are made special by the rainbow-colored inclusions that reflect the light as the stone is moved. Black opals are much rarer, because almost all of them are found in mines in the Lightning Ridge area of New South Wales in Australia. The darker their background color and brighter the inclusions, the more valuable the stone. One of the most valuable black opals of all time is the “Aurora Australis,” which was uncovered in Lightning Ridge in 1938. The 180-carat opal is especially admired due to its large size and intense harlequin coloration; in 2005 it was valued at AUS $1,000,000, or about $763,000 U.S.

3. LARIMAR // ONLY FOUND IN THE DOMINICAN REPUBLIC

Larimar is a very rare blue variety of the mineral pectolite and is found in only one small area of the Dominican Republic. This turquoise stone’s name was created by the man who brought the stone to prominence in 1974, Miguel Méndez—he took the first part of his daughter’s name, Larissa, and combined it with the Spanish word for sea, mar, to create the portmanteau larimar. Locals had known of the existence of the stone for generations, because small examples had washed up on the seashore, but it was not until the 1970s that sufficient quantities were found in the ground to open a mine.

4. PARAIBA TOURMALINE // NEON LUSTER

Tourmalines are common in many colors across Brazil, but the Paraiba tourmalines are the only stones with a bright turquoise hue, thanks to their copper content. The very rare gems were discovered in 1987 by determined miner Heitor Dimas Barbosa, who had been driven by a belief that something special lurked under the hills of the Brazilian state of Paraiba. Barbosa was right, and after years of fruitless digging, he finally unearthed a tourmaline of unrivaled neon blue that set the gem market alight. In 2003 these turquoise-colored tourmalines were found at mines in the mountains of Nigeria and Mozambique. The extremely rare stone (only one stone is mined for every 10,000 diamonds) then became intensely sought-after.

5. GRANDIDERITE // ONE EXCEPTIONAL EXAMPLE

Grandiderite was first described in 1902 by French mineralogist Alfred Lacroix, who found it in Madagascar and named it in honor of the French explorer Alfred Grandidier, an expert on Madagascan natural history. This extremely rare blue-green mineral has been found in a number of places around the world, but so far only Madagascar and Sri Lanka have produced any gem-quality stones, and these are still extremely scant. The majority of the known stones are translucent, but the most rare, and therefore most valuable, example ever found was transparent. In fact, the stone was initially assumed to be another rare gem, serendibite, because grandiderite of that color and transparency had yet to be seen. The gem was only identified as grandiderite after expert analysis and was subsequently sold for an undisclosed sum. It’s safe to assume that if a gem of similar quality were to be unearthed, its scarcity alone would ensure it fetched an extremely high price.

6. ALEXANDRITE // COLOR-SHIFTING GEM

The amazing color-changing stone alexandrite was discovered in 1830 in the Ural Mountains in Russia and named after Russian tsar Alexander II. A variety of chrysoberyl, the stone’s remarkable color-shifting capability makes it especially sought-after: In sunlight the stone looks blue-green, but under incandescent light it becomes red-purple. The degree of color change varies from stone to stone, with some only showing marginal change, but the most valuable are clear stones that demonstrate complete color change.

Although some large examples of the stone have been found (the Smithsonian houses the world’s largest known cut sample of alexandrite at 65.08 carats), the majority are under one carat. This means that the value of a gem under a carat may only be $15,000, but a stone larger than one carat might fetch as much as $70,000 per carat.

7. BENITOITE // STATE GEM OF CALIFORNIA

Benitoite is only mined in one small area of California, near the San Benito River (hence the name), but the mine closed for commercial mining in 2006, making this gemstone yet more scarce. The gem was first identified around 1907 by geologist George Louderback and has a deep-blue color that shows especially interesting qualities when caught under UV light, when it glows fluorescent. The gem was named the official state gemstone of California in 1985 in recognition of the fact that, despite it being found in trace quantities in Arkansas as well as Japan and Australia, California is the only place where it can feasibly be mined. Due to the rarity of discovering a good quality benitoite of a reasonable size, it can fetch huge prices on the open market—a well-cut benitoite stone at over 2 carats can fetch more than $10,000 a carat.

8. PAINITE // ONCE THE WORLD’S RAREST GEM

Painite was first discovered by British gemologist Arthur Charles Davy Pain in 1951 and recognized as a new mineral in 1957. For many years only one specimen of the dark red crystal was in existence, housed at the British Museum in London, making it the world’s rarest gemstone. Later on other specimens were discovered, although by 2004 there were still fewer than two dozen known painite gems. However, in recent years a couple of mines in Myanmar have begun to produce some painite, and there are now said to be over 1000 stones known. The scarcity of this gem has made it extremely valuable and just one carat can fetch more than $60,000.

9. RED BERYL // TINY AND SCARCE

Red beryl, also known as bixbite or red emerald, is so rare it is estimated by the Utah Geological Survey that a single such gem is uncovered for every 150,000 gem-quality diamonds. Pure beryl is colorless and only gains its bright hues from impurities in the rock: chromium and vanadium give beryl a green color resulting in an emerald; iron provides a blue or yellow tint creating aquamarine and golden beryl; and manganese adds the deep-red color to create red beryl. Red beryl is only found in Utah, New Mexico, and Mexico, and the majority of examples found are just a few millimeters in length, too small to be cut and faceted for use. Those that have been cut are generally less than a carat in weight, and a red beryl of 2 or 3 carats would be considered exceptional.

10. TAAFFEITE // DISCOVERED BY CHANCE

Austrian-Irish gemologist Count Edward Charles Richard Taaffe bought a box of cut stones from a jeweler in Dublin in the 1940s, thinking he had purchased a collection of spinels. But on closer inspection, he noted that one of the pale mauve gems was not reacting to the light in the same way as the rest of the spinels, so he sent it off to be analyzed. The results revealed that he had discovered a hitherto unknown gemstone—a serendipitous but frustrating situation, since he had discovered a cut gem and had no idea where the mineral naturally occurred. Fortunately, once the new stone had been announced, many other collectors re-examined their own spinel collections and a number of other samples were uncovered. Finally the source of the stone was tracked down to Sri Lanka, although a handful have also been found in Tanzania and China. It is thought that less than 50 examples of taaffeite exist—many of which are housed in geological and private collections, making this gemstone so rare the ordinary public are unlikely to ever encounter it.

From Mental Floss