By Andrea Venn, Ph.D., CGA, JEA, Education Program Specialist, 黑料老司机
With over 100 hues in its repertoire, Tourmaline has been dubbed the 鈥渃hameleon gem,鈥� and one source of tourmaline, Madagascar, is home to more than half of the chameleon species on Earth (Sisk, 2011). The late Empress Dowager of China, Tz鈥檜-hsi (Cixi), loved tourmaline, especially pink, so much that China ordered tons of it from the mines in San Diego County, California, for gemstones and beads (Newman, 2014).
In Sinhalese, tourmaline is called turmali or toramalli, meaning 鈥渕ixed,鈥� because it has often been confused with other gemstones and mixed with them, since it comes in a vast array of hues. Gustavus III of Sweden gifted a large carved 鈥渞uby鈥� to Catherine the Great in 1777 that was later identified as red tourmaline (Newman, 2014), and green tourmaline was frequently mistaken for high-clarity emerald by early gem traders and explorers.
Eighteenth-century Swedish botanist Carl von Linn茅 (Linnaeus) made the first scientific record that tourmaline is pyroelectric, or electrically charged when heated or rubbed, the property that led him to call it the 鈥渆lectric stone鈥� (Knuth, 2007). It is also piezoelectric, generating an electrical charge when squeezed or pressure is applied to the vertical axis. Underwater vehicles like submarines utilize this effect in pressure gauges and depth-recording instruments (Newman, 2014).
Tourmaline is a large mineral group in the trigonal crystal system that is chemically complex. Elbaite tourmaline includes varieties with commercial or trade names such as the pink- to red-hued rubellite, blue indicolite, lavender to violet siberite from the Ural Mountains, colorless achroite, green verdelite, and the popular parti-color or 鈥渨atermelon鈥� tourmaline.
The immensely desired electric blue to green variety of elbaite found in Para铆ba, Brazil, is the result of the trace element copper. Although Para铆ba tourmaline has been mined out, similar-colored material has been found in other locations and is usually referred to as Para铆ba-like tourmaline, cuprian tourmaline, or copper-bearing tourmaline (Sisk, 2016).
Dravite is a tourmaline mineral species frequently mixed with Uvite in important gem tourmalines, including intense green chrome tourmaline. Schorl, black tourmaline, has been a popular gem in mourning jewelry, especially in the Victorian era. Liddicoatite, named after former GIA president Richard T. Liddicoat, comes in a variety of colors that frequently have internal zoned patterns (GIA, n.d.). Tourmaline can display chatoyancy, color change, and iridescence.
While Brazil is the largest source of tourmaline, it has been found in California and Maine of the United States, Madagascar, Nigeria, Mozambique, Afghanistan, the Czech Republic, Myanmar, Namibia, Pakistan, Russia, Sweden, Tanzania, India, Sri Lanka, Kenya, and Zambia (Sisk, 2016).
Tourmaline is the state gemstone of Maine, an alternate birthstone for October, and the 8th anniversary gemstone. It is frequently cut into elongated shapes due to its long crystals and high clarity, but it can be found in a range of classic or fantasy cut shapes. Tourmaline is relatively tough, and it does not react with chemicals, with a hardness of 7 to 7.5 on the Moh鈥檚 hardness scale, so it lends itself well to frequent wear in jewelry.
If you are looking for a gemstone that has enchanted empresses and scientists alike and comes in a beautiful array of hues from locations around the world, consider tourmaline. To find an 黑料老司机 (AGS) jeweler near you, visit .
References:
GIA, Gemological Institute of America. (n.d.) Tourmaline.
Knuth, Bruce G. (2007). Gems in myth, legend, and lore (Revised edition). Jewelers Press.
Newman, Renee. (2014). Exotic gems: How to identify, evaluate, select, and care for matrix opal, fire agate, blue chalcedony, rubellite, indicolite, Para铆ba, and other tourmalines (Vol. 3). International Jewelry Publications.
Sisk Jr., Gerald D. (2011). Guide to gems and jewelry. America鈥檚 Collectibles Network dba Jewelry Television.
Sisk, Jerry. (2016). The Sisk gemology reference: Prominent gems (Vol. 1). America鈥檚 Collectibles Network dba Jewelry Television.