Tourmaline

Tourmaline is the gemological name for an important group of complex gem-quality boron silicate minerals. Tourmaline gemstones can be found in all colors of the rainbow. Owing to its wide range of color availability, tourmaline is considered to be one of today’s most versatile gemstones. Its name is thought to be derived from the Sinhalese word, “turamali”, which means “stone with various colors” in reference to its extreme versatility. Tourmaline was first thought to be used as a gemstone around the 1500s, but distinct mineral species were not actually described until the 1800s. In 1875, George Kunz, an American mineral collector, introduced green tourmaline from the Mount Mica mine in Maine, USA to Tiffany & Co., which sparked an interest in tourmaline and led to its popularity (along with other semi-precious gemstones) on the mainstream jewelry market.

The major tourmaline species include dravite, uvite, schorl, liddicoatite and elbaite. Schorl is the most common variety, making up nearly 95% of all tourmaline deposits, but it is not often desired as a gemstone. Most tourmaline gemstones are varieties of the elbaite family. Since tourmaline consists of a very large group of related gemstones, most tourmaline is traded under very color-specific varietal names. Some of the more popular trade names include pink-red ‘rubellite’, blue-green ‘Paraiba’, blue ‘indicolite’ and multicolored ‘watermelon tourmaline’. Lesser-known trade names include colorless ‘achroite’, green ‘verdelite’ and ‘chrome tourmaline’. Like sapphire, descriptive names such as ‘yellow tourmaline’ or ‘pink tourmaline’ are also commonly used to market fancy-colored tourmaline gemstones.

Tourmaline Color

Tourmaline can occur in a wide range of colors from colorless to black. Colorless tourmaline is considered to be the rarest, but it is also the least valuable tourmaline. Black tourmaline is actually the most common color occurrence. Most tourmaline gemstones display two or more colors in a single stone (or two tones of the same color). Tourmaline crystals that exhibit green on one end and pink to red on the other, with a band of white in the middle are marketed as ‘watermelon tourmaline’. Tourmaline exhibits strong pleochroism, which means its crystals can exhibit different colors depending on the angle from which they are viewed. Most red, pink and brown to yellow tourmaline is colored by manganese, while iron and titanium can result in greenish to bluish-black colors. Lithium impurities can result in just about every color, including blue, green, red, yellow and pink. The rare emerald-green chrome tourmaline is colored by chromium (and sometimes vanadium). Many pink tourmaline crystals obtain their color though a natural irradiation process. Cat’s eye tourmaline is typically green or pink in color, although it can also occur in other rarer colors too. The most valuable and rare tourmaline is neon green-blue Paraiba tourmaline, which is colored by copper. Other valuable color combinations include purplish-red ‘rubellite’ and blue ‘indicolite’. When buying tourmaline, color intensity and saturation are the most important factors.

Tourmaline Clarity and Luster

Tourmaline is typically transparent to translucent. Opaque material is common for cat’s eye tourmaline and schorl. According to GIA, most tourmaline is ‘Type II’ material in regard to clarity, which means tourmaline is often included. The level of inclusions can vary depending on the type of tourmaline, with some colors being more heavily included than others. Green tourmaline is often eye-clean, while blue, red and pink tourmaline, including rubellite, Paraiba and watermelon tourmaline, are almost always found with significant inclusions. Rubellite, Paraiba and watermelon tourmaline are considered to be Type III clarity gems. Cat’s eye tourmaline is usually translucent to opaque and owes its chatoyancy to thin needle-like inclusions. When cut and polished, tourmaline exhibits a vitreous to sometimes slightly resinous luster.

Tourmaline Cut and Shape

Tourmaline is often cut into long rectangular bar shapes because of its elongated crystal habit. However, tourmaline is also available in various traditional and fancy shapes and a range of cutting styles. Due to the strong pleochroism of tourmaline, lighter colored tourmaline is typically oriented with the table facet perpendicular to the main axis, in order to display the richest hue. Conversely, darker stones are usually cut with the table parallel to the main axis. Rare cat’s eye tourmaline is cut en cabochon to best display the desirable cat’s eye chatoyancy. Watermelon tourmaline is often cut into slices to best exhibit its characteristic and attractive color zoning.

Tourmaline Jewelry

Tourmaline is an extremely versatile gemstone, due to its great diversity of colors and tones. There is a color and shade of tourmaline to suit every taste and skin tone. When designing tourmaline jewelry, the preferred color can be first considered. Tourmaline jewelry can be vivid and striking or subtle and understated. Intense pink tourmaline, emerald green and Paraiba tourmaline gemstones are often accented with diamonds in rings by Chopard, Chanel, Dior and Cartier. Both white and yellow precious metal settings are equally stunning. Tourmalines make beautiful central stones and are often available in large, affordable sizes. Smooth, unfaceted tourmaline beads are used in tribal-style jewelry and wire-wrapping. Tourmaline is perfectly suitable for tough everyday-wearing tourmaline gemstone rings, and fashion jewelry too, including bracelets, pendants, earrings and brooches. Additionally, men’s jewelry can be fashioned from the more masculine-hued gemstones.

Source: Gem Select