TOURMALINE: All the Shades of the Rainbow
Tourmaline occurs in a wider range of colors than any other gemstone. Although the general public does not know tourmaline as well as some other gems, it is increasing in popularity. The fashion industry, with its increasing use of bright colors in clothing, has created an unprecedented demand for brightly colored natural stones, which has benefited this lovely gemstone. Tourmaline's name comes from the Sinhalese word "turmali," which means "mixed." Bright rainbow collections of gemstone varieties were called "turmali" parcels. Originally, native miners applied this term to mixed parcels of gems when they didn't really know exactly what the stones were.
Tourmaline occurs in virtually every known gemstone color, with more than 120 distinct hues reported. Greens, blue-greens, blues and pinks are typical, and these are the most in demand commercially. The red shades are also in great demand, but are rare and harder to acquire. The tourmaline palette also includes lesser known shades of yellow, orange, brown, violet and other subtle colors that one would expect to find in a rainbow, rather than a jewelry shop. Many tourmalines are color-zoned; a cut gemstone may therefore display several hues, sometimes with the color bands sharply delineated. Tourmaline crystals grow in the hexagonal shape and tend to be long, pencil shape crystals. This crystal shape is the reason why long rectangular cuts are so frequently seen in Tourmaline.
Green tourmalines of the best hue actually resemble emeralds, and are widely used as a kind of emerald stimulant. In the sixteenth century green tourmalines from Brazil were thought to be emerald. But most tourmaline colors, being intense, stand on their own merits. At times, tourmalines, especially green stones, may actually be too dark in saturation, which allows less sparkle out of the stone. Stones are easily available in sizes up to 5 carats. Large, flawless tourmalines are becoming increasingly rare, however. Investment-grade stones are generally of fine color and flawless, in sizes over 10 carats. Much larger stones are also available, but a flawless green tourmaline over 40-50 carats may be considered worthy of museum display. Since most tourmalines, even these exceptionally large ones, sell at prices measured in terms of hundreds of dollars per carat, they must be regarded as having great potential for future appreciation.
Ruby and spinel are priced at levels of thousands of dollars per carat. Red tourmaline of a similar color therefore, at several hundred dollars per carat, remains an attractive value and one that has significant potential for price appreciation. Red tourmalines, especially ones that resemble fine ruby, are so rare that they are almost never seen in jewelry stores, and remain essentially unknown to the public. Typical rubellite colors include pink, rose-red and violet, and intermediate shades. The chemical impurities that color a tourmaline red or pink are detrimental to the stable growth of the material in its natural environment. These impurities cause a growing tourmaline crystal to become internally flawed or cracked; the more the impurity is present, the darker the red color, and the more imperfect the final crystal. It is therefore extremely rare to find dark violet, pink or red tourmalines that are "clean" internally. Some day in the future the gemstone market will be fully aware of this fact, and fine rubellite will be priced accordingly.
|Many Tourmalines exhibit pleochroism, the variation of colors visible in different axial directions of the crystal. Sometimes the colors are at different ends of the crystal and sometimes there is one color in the heart of the crystal and another around the outside. One color combination, pink center with a green rind, is called "watermelon tourmaline". Sometimes designers set slices of the crystal instead of faceted stones to show off this phenomenon. The cutter must always cut the table parallel to the main axis to produce a stone with vivid color. Tourmaline is also of interest to scientists because it changes its electrical charge when heated. It becomes a polarized crystalline magnet and can attract light objects. This property was noticed long ago before science could explain it: in the Netherlands, tourmalines were called "aschentrekkers" because they attracted ashes.||
TOURMALINE FROM AROUND THE WORLD
Tourmalines are found mainly in Brazil, Sri Lanka, Africa and the
U.S. In 1822, red and green tourmaline was discovered in Maine and as this new source
produced sufficient quantities of gemstones, a new market was created and gave tourmaline
value. California became a large producer of tourmaline in the early 1900s. Maine produces
beautiful sherbet colors of tourmaline and spectacular minty greens. California is known
for perfect pinks, as well as beautiful bicolors. During this time, Maine and California
were the worlds largest producers of gem tourmalines. The Empress Dowager Tz'u Hsi, the
last Empress of China, loved pink tourmaline and bought almost a ton of it from the then
new Himalaya Mine, located in San Diego County, California. The Himalaya Mine is still
producing small quantities of tourmaline today.
Tourmaline is the most common boron bearing silicate mineral and is almost exclusively found in geological formations known as pegmatites, where gem quality stones occur in open pockets in the pegmatite dikes. The color in tourmaline is a result of substitutions of various transition elements or metals in the crystal structure. It is not uncommon that a pocket of Tourmaline crystals may contain stones several different colors.
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TREATMENTS FOR TOURMALINE
The color of tourmaline can sometimes be improved by heat treatment and or irradiation. These treatments are often permanent and generally accepted in the gemstone trade. However, only a comparatively small portion of tourmaline gemstones on the market are treated by either heating or irradiation - most, especially the green colors, are natural.
CHOOSING A TOURMALINE
The purity and intensity of color and clarity are the most important
qualities to evaluate tourmaline. The most valued of tourmalines is the Paraiba by far.
The exceptionally bright colors of Pariba command prices approaching $10,000 per carat.
Red Tourmaline is called Rubellite because the deepest shades appear to be Ruby-like. Eye
clean Rubellite is one of the most expensive of the Tourmalines because generally it is an
included stone - clean Rubellite is very rare. Rubellite's intense color makes it a
beautiful Gem for mounting. Colors range in Rubellite from Fuchsia to maroon Red to Red.
The price of Rubellite goes up dramatically as the size increases or the Red deepens in
intensity, though nothing close to the price of Pariba material. Fine blue tourmalines
(indicolites), blue/green, bi-color, parti color can also command good prices. Pink
and green tourmaline are now widely available and are especially popular in designer
jewelry. Blue tourmalines are also very much in demand but the supply is more limited.
The purity and intensity of color and clarity are the most important qualities to evaluate tourmaline. The most valued of tourmalines is the Paraiba by far. The exceptionally bright colors of Pariba command prices approaching $10,000 per carat. Red Tourmaline is called Rubellite because the deepest shades appear to be Ruby-like. Eye clean Rubellite is one of the most expensive of the Tourmalines because generally it is an included stone - clean Rubellite is very rare. Rubellite's intense color makes it a beautiful Gem for mounting. Colors range in Rubellite from Fuchsia to maroon Red to Red. The price of Rubellite goes up dramatically as the size increases or the Red deepens in intensity, though nothing close to the price of Pariba material. Fine blue tourmalines (indicolites), blue/green, bi-color, parti color can also command good prices. Pink and green tourmaline are now widely available and are especially popular in designer jewelry. Blue tourmalines are also very much in demand but the supply is more limited.
Natural Tourmaline crystals are sometimes very beautiful, pencil thin and ridged, and they are sometimes set in jewelry in their natural form. Any of the Tourmaline colors can be used as one of the birthstones for October. Tourmaline is also the 8th wedding anniversary Gemstone. Tourmaline is one of the accepted birthstones for October and the accepted anniversary gemstone for the eighth year of marriage. Some designers also set rainbows of tourmaline in each color of the spectrum. A "rainbow" bracelet of 30 or more tourmalines, each one a different color, is an ideal gift for very special occasions! Tourmaline jewelry should be cleaned in warm, soapy water with a soft brush. Do not clean tourmaline a home ultrasonic machine, especially rubelite. It is also sensitive enough that it should be protected from scratches and sharp blows.
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