Tourmaline, along with opal, is the birthstone for October. It is a complex borosilicate gemstone made of aluminum, magnesium and iron and comes in a rainbow of colors. Indeed, tourmaline is believed to have the greatest color range of any gemstone. In some gems, the colors can change depending on the angle through which they are viewed. Other examples of tourmaline have more than one color, and some tourmaline stones are cat's eyes.
There are several types of tourmaline, including:
•Watermelon: This type of tourmaline has a pink center and a green edge, thus giving it its name.
•Bicolor: This has two colors, often green and pink, along the length of the crystal.
•Paraiba: These tourmaline stones are a beautiful electric blue. Paraiba tourmaline stones are also among the most expensive. They can cost as much as high quality diamonds.
•Chrome: Jewelers use chrome to color this type of tourmaline a brilliant green.
•Rubellite: The color of this tourmaline ranges from brilliant red to bright pink.
•Indicolite: This tourmaline is dark blue.
•Schorl: This is a black tourmaline.
•Dravite: This tourmaline is brown.
Pink, blue and green are the most popular colors for tourmaline stones. The color of a tourmaline can be lightened, darkened or made more intense through heating. Some tourmaline stones turn red when they are irradiated.
Tourmaline stones are also pleochroic, which means that the deepest color is seen when looking down the length of the crystal. Looking at a tourmaline this way can make a green or blue color seem black, so great care is taken when cutting this stone.
Tourmaline is often used in rings, as can be seen in the
pink tourmaline ring displayed here, from Nancy B. They're also seen in stud earrings, like the
cushion cut, pink tourmaline stones that highlight a pair of earrings that are also from Nancy B. They also go very well with other gemstones such as diamonds, as can be seen in a ring from Nancy B that features a cushion cut green tourmaline flanked on each side by three small diamonds in a channel setting.
How It's Cut
Tourmaline is often faceted, and the emerald cut is one of the most popular cuts. The straight facets of this cut come naturally to tourmaline because it usually comes in a long crystal. The cut also shows off the rich color of the gem to its best advantage. If the gem has more than one color, the lapidist cuts it in a way to show off both colors. Round tourmaline cuts, like those found in the rings and earrings offered by Carla/Nancy B, are fairly rare, especially if they are large. Tourmaline stones with a beautiful play of different colors are the most expensive and the most challenging to cut.
Tourmaline is a fairly hard stone, with a ranking of 7 to 7.5 on the Mohs hardness scale. By contrast, a diamond is ranked a 10. Tourmaline is fairly tough and has a glass-like luster. Many tourmaline stones have wavy inclusions in them that can make them subject to fracturing if they're knocked.
Where It's Found
Tourmaline stones are found in granites and pegmatites, which are rocks formed in volcanoes. Good quality tourmaline is found in Mozambique, Namibia, Brazil, Pakistan, the United States and Russia.