For people who love colored gemstones, tourmaline has long been a favorite. It is valued for its incredible range of colors and its vitreous luster. It has also been a very affordable gem, even in larger sizes, with the exception of some very rare tourmaline varieties which can be quite expensive.
Tourmaline is a family of boron silicate minerals. It has a complex chemical composition, with many permutations. Mineralogists recognize 14 different varieties of tourmaline, with the boron silicate compounded with aluminium, iron, magnesium, sodium, lithium or potassium. Most of the tourmalines used as gemstones are the lithium-rich stones known as Elbaite. They can occur in almost any color, especially blue, green, red, yellow and pink.
Prices for fine tourmaline also exhibit a wide range. The rarest and most expensive tourmaline is the paraiba variety -- a neon-like blue or green that is colored by traces of copper. It was first discovered in the Brazilian state of Paraiba in 1989. In 2001 some similar material was discovered in Nigeria, though the color saturation was not as good as the Brazilian stones. Then in 2005 a third find was made, this time in Mozambique. The Mozambique material ranges in color from green to blue-green to violet, and can be comparable to the Brazilian paraiba. Indeed the Mozambique Paraiba is often cleaner than the Brazilian (which tends to be heavily included) and is sometimes found in larger sizes.
But paraiba tourmaline is so scarce that prices are difficult to define. Fine Brazilian material is the rarest and most expensive. Clean stones 2cts to 4cts with vivid color can easily command prices well over $25,000 per carat and over 10cts up to $53,000 per carat, with Mozambique stones usually less. Color and clarity have an enormous affect on paraiba prices.
Pink Tourmaline Blue Green Tourmaline Yellow Tourmaline Fancy Tourmaline
The red to purplish-red rubellite is typically the second most expensive of the tourmalines. Pure red rubellites can be found, but they are very rare. The most typical color is an intense pinkish or purplish-red that is one of the most vivid colors found in any gemstone variety.
Rubellite typically has significant inclusions. So long as the inclusions do not make the gem appear milky or cloudy, they do not affect the value of a finely-colored stone. High quality rubellites can cost $800 to $1,500 a carat depending on color, size and clarity.
Chrome tourmaline is a rare emerald-green tourmaline colored by chromium and vanadium. Similar in color to tsavorite garnet, it is found in the same locations in East Africa. The color of chrome tourmaline is so intense that high quality stones are generally found only in smaller sizes. Chrome tourmalines over 2 carats tend to be dark and overcolored, and larger specimens with a brighter color are particularly rare and valuable. Prices are in the range of $1,500 to $2,500 a carat for high quality gems.
Tourmaline is famous for bi-color and tri-color stones that display two or more areas of different colors. Most often they feature a combinations of pink and green or some variation. The color range is quite wide, ranging from orange to purple to brownish-pink and blue-green to apple-green. These multicolor stones are popular with collectors and high quality specimens sell for prices in the range of $400 to $700 per carat.
Other colors of tourmaline tend to be less expensive, but any fine material with vivid color can be quite valuable, especially in larger sizes. Among the other tourmaline colors, the vivid pinks and the blue-greens are noteworthy as are the hard-to-find yellows. The least expensive tourmalines, the opaque black stones known as schorl, are only occasionally used as gemstones.