There are a plethora of different names and categories for the Tourmaline gemstone family, which is generally divided into the following sub-groups: Dravite, Schorl and Elbaite, which is named after the Italian island of Elba.

Birthstone Month:
Tourmaline is one of the two gemstones associated with the month of October.

Zodiac:
Being one of the two accepted birthstones for the month of October, Tourmaline is one of the zodiac gemstones for Libra and Scorpio.

Chemical Symbol:
(Na, Ca)(Li, Mg, Al)(Al, Fe, Mn)6(BO3)3(Si6O18)(OH)4

Chemical Make-up:
The actual elements in Bi-Color Tourmaline gemstones vary. The colors displayed by Tourmalines are dictated by the prescence of various metal ions.

History & Lore:
The name Tourmaline is widely accepted as being derived from the Singhalese expression tura mali, which when translated means “stone of many or mixed colors”.

Tourmaline is often referred to as the rainbow gemstone, due to the huge amout of colors that it is available in. This was certainly believed by the ancient Egyptians who believed that when Tourmaline traveled from its home in the earth's core to the surface, it did so along a rainbow, which subsequently gifted the gemstone with all of the colors of the rainbow.

Tourmalines exhibit piezoelectricity and when these stones become warm they become electrically charged – positively at one end and negatively at the other, acting like a magnet and strong enough to attract small particles of dust or ash. It is for this reason that the Dutch of old used Tourmalines to clean their pipes!

Availability:
Tourmaline is a widely available gemstone. Currently supply meets demand, but Bi-Color Tourmalines do have a tendency to be quite heavily included. Having said this, Bi-color Tourmalines with vivid, well-divided colors and few or no eye-visible inclusions can be found, are highly desirable and are truly beautiful.

Sources:
There are known Tourmaline deposits throughout the world including, Afghanistan, Africa, Brazil, Italy, Kenya, Madagascar, Mozambique, Myanmar (Burma), Nigeria, Pakistan, Siberia, Sri Lanka, Tanzania and the United States (California, Connecticut, Maine and Utah).

Evaluation:
Tourmaline (regardless of variety) is rated at 7 – 7.5 on the Moh's Scale of Hardness and as such is suitable for all jewelry uses and is considered durable enough to be worn everyday.

Found in an amazing variety, the sheer number of available Tourmaline colors is second to none and unmatched by any other gemstone. Tourmalines can be found in shades of blue, black, brown, colorless, green, orange, pink, red, yellow and other colors in varying shades and hues, varying from completely transparent to opaque. In addition to this there are also known occurances of bi-color, tri-color, mulit-color and “Cat's Eye” Tourmalines, ensuring that the Tourmaline truly is a gemstone that is available in a color to suit all styles and tastes.

A Tourmaline gemstone viewed from different angles will result in differing color intensities being visible. The only one thing that you can be sure of is that the deepest coloration will always be shown along the stone's main axis. When selecting a Tourmaline, go with the color that you like but generally try to steer clear of any stone that is cut too dark.

Arguably the most desirable and valuable Tourmalines in today's market are known as “Paraiba” Tourmaline. These are vivid deep blue to bluish-green in color and originate from the Paraiba state in Brazil. Expect to pay a premium for this variety. There is also currently strong demand for the “Verdelith” Green Tourmaline and Pink Tourmaline (Pink Rubellite), both of which are priced reasonably moderately. Demand is also increasing expotentioally for many of the varieties of Bi, Tri and Multi-colored Tourmalines, most notably “Watermelon” Tourmaline, which are bi-colored stones with a green border enveloping a red center.

These “Watermelon” Tourmalines are presently enjoying strong demand, but for the moment pricing remains reasonable. When condsidering buying a “Watermelon” or any other Bi-color Tourmaline for that matter, pay particular attention to color seperation and be sure to select a stone that does not suffer from numerous heavy inclusions as these will have a detrimental effect on the overall worth of the gemstone.

Common Cuts:
Owing to the fact that Tourmaline crystals are long and narrow in shape Tourmaline gems are most commonly, although not exclusively cut into square or rectangular stepped shapes.

Routine Enhancements:
Tourmalines are often heat-treated in order to lighten colors and to remove “silk” (a form of natural imperfection / inclusion). Some colored Tourmalines actually transform into other Tourmalines (most commonly the Achroite Tourmaline variety), during this heating process.

Care & Cleaning:
Use warm, soapy water and a soft brush to clean Tourmaline. Ultrasonic cleaners are generally safe. Never use chemicals such as hydrofluoric acid or ammonium fluoride to clean Tourmaline because it can erode the stone. Much like many gemstones, Tourmaline should be kept away from prolonged exposure to extremes of heat and light as this can cause permanent color change.