Traditional Gem: Tourmaline
Modern Gem: Opal, Tourmaline
Chemically speaking, tourmaline is a complex aluminum and boron silicate mineral. Colors are red, pink, blue, green, yellow, violet, and black; sometimes it is colorless. Two or more colors, arranged in zones or bands with sharp boundaries, may occur in the same stone. Tourmalines are found in pegmatite veins in granites, gneisses, schists, and crystalline limestone. Important sources include Elba, Brazil, Russia, Sri Lanka, and parts of the U.S. Tourmaline scores a 7.0 on the Mohs scale.
Tourmaline occurs in every color of the rainbow and combinations of two or three colors. Bicolor and tricolor tourmalines, with bands of colors are very popular. 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" (seedless, of course!) Sometimes designers set slices of the crystal instead of faceted stones to show off this phenomenon.
Almost every color of tourmaline can be found in Brazil, especially in Minas Gerais and Bahia. Pink and green colors are particularly popular. In 1989, miners discovered tourmaline unlike any that had ever been seen before. The new type of tourmaline, which soon became known as Paraiba tourmaline, came in incredibly vivid blues and greens. The demand and excitement for this new material, which soon fetched more than $10,000 per carat, earned more respect for the other colors of tourmaline.
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. Rubellite tourmalines, which come in a ruby red color, are very popular as ruby alternatives.
Tourmalines are most often cut in long rectangular shapes because of their long and narrow crystal shape. Tourmaline crystals are beautiful, pencil thin and ridged, and they are also sometimes set in jewelry. Some designers also set rainbows of tourmaline in each color of the spectrum. Tourmaline is strongly pleochroic: the darkest color is always seen looking down the axis of the crystal.
In addition to Brazil, tourmaline is also mined in Tanzania, Kenya, Madagascar, Mozambique, Namibia, Afghanistan, Pakistan, Sri Lanka, and California and Maine in the United States. Maine produces beautiful sherbet colors of tourmaline and spectacular minty greens. California is known for perfect pinks, as well as beautiful bicolors.
One particularly beautiful variety is chrome tourmaline, a rare type of tourmaline from Tanzania which occurs in a very rich green color caused by chromium, the same element which causes the green in emerald. Tourmaline is a hard and durable gemstone which can withstand years of wear.
Tourmaline's name comes from the Sinhalese word "turmali," which means "mixed." Bright rainbow collections of gemstone varieties were called "turmali" parcels. Tourmaline, occurring in more colors and combinations of colors than any other gemstone variety, lives up to its name. There is a tourmaline that looks like almost any other gemstone! Many stones in the Russian Crown jewels from the 17th Century once thought to be rubies are actually tourmalines.
Perhaps this is why this gemstone is said to encourage artistic intuition: it has many faces and expresses every mood.
The Empress Dowager Tz'u Hsi, the last Empress of China, loved pink tourmaline and literally bought almost a ton of it from the New Himalaya Mine, located a long way from the Middle Kingdom in California. The Himalaya Mine is still producing tourmaline today but the Dowager went to rest eternally on a carved tourmaline pillow.
Pink Tourmaline shares October's birthstone status with opal.
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 and could be used to clean pipes!
Tourmaline is a varied and versatile gem. It comes in every color, and as with all colored gems the most expensive will be the ones with the brightest colors. Because long tourmaline crystals sometimes show two colors, these shapes will be set into jewelry. Once again, the two colors--their respective vividness and their collective contrast--will determine price.
The most expensive varieties are the green chrome varieties from Tanzania, and the amazing bluish Brazilian stones know as Paraiba tourmalines. Chrome tourmalines rival emeralds in color, and cost almost as much. Paraiba tourmalines are even rarer and more expensive and rank among the most precious of gems, with colors and prices that rival the finest sapphire and tanzanite.
Fine green tourmalines can run close to a thousand dollars a carat, but are more often closer to about half that price. Because they often show an excellent green color, they are a good substitute for more expensive emeralds or tsavorites. Pink tourmalines usually cost even less, depending on color saturation--the preferred colors are bright lemonade pink and a cranberry-red. Tourmalines that are ruby colored are called rubellite tourmalines, and they cost more. There's ample proof that rubellite tourmalines make excellent ruby substitutes--royal families were fooled for centuries.
Most tourmalines are heat treated to improve color. This process is permanent and stable. Tourmalines are also commonly irradiated to improve color. Unlike with some other gems, irradiation is a stable and permanent process with tourmalines. Since tourmalines are not especially prone to inclusions, oil treatments or fracture filling are rare.
Tourmaline rank around 7-7.5 on the Mohs scale of hardness, and can be set in a variety of ways safety. They are less prone to chipping than emeralds or other gems that have more inclusions. Tourmalines can be safely cleaned with warm water and mild soap, but mechanical cleaners should be avoided.