447 Natural green tourmaline, 3.74ct. 10x7x4mm, emerald cut , Brazil

Description

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.