TOURMALINE

The tourmaline's have been found in Sri Lanka (Ceylon). Their name comes from the Sinhalese "turamali" which means a mixture of yellow stone. Although known to Europeans since ancient times, they were imported in the West until the early 18 th century by Dutch sailors. Noting that these stones attracted ashes of their pipes, they named them "Aschentrekker" which means "that attracts the ashes." The tourmalines are therefore the physical property to be pyre-electric: they electrifying under heat and attract dust particles.

The Tourmaline's come in a wide variety of colors:

The Paribas, discovered in 1989 (Brazil), is blue or green power;

The verdelite has several shades of green, emerald green being the most popular;

The Indicolite presents various shades of blue;

The Rubellite is pink to purplish red, the ruby is much appreciated;

The schorl, rarely used in jewelry, is black;

The Anchorite, rare variety, is colorless;

The "Watermelons" are bicolor (red and green) and other lights.

The color of tourmaline's can be modified by various processes. By heating to 600 degrees centigrade, take the green shades of emerald and red shades of brown, becoming bright red. The most productive deposits are located in Brazil, Sri Lanka and Madagascar. The purest and most transparent from Afghanistan. They are found in Tanzania (chromate green) and the United States (watermelon).

Tourmaline is tough, durable, and bright and offers a range of colors richer. It is one of the most popular precious stones and the most sought after by collectors around the world. While most are inexpensive, some selling prices reach astronomical. Chrome tourmaline, inviolate jubilates quality and can reach $ 500 a carat. Paribas tourmaline, whose colors green, blue or lilac so litigious earned him sometimes to be called "neon", can reach and exceed $ 3,000 a carat.

Characteristic

    Crystal system: Trigonal

    Chemical composition: Borosilicate complex.

    Colors: Toutesles colors. Pink, red and green are the most requested, however.

    Hardness: 7.0 to 7.5

    Specific gravity: 3.06

    Refractive index: 1624-1644

    Dispersion: 0017

    Polychrome: Weak to strong. Varies by color.

    Birthstone: October.