Blue Tourmaline

Most gem tourmalines are elbaites, which form in granite-containing pegmatites; different pockets in one pegmatite can yield crystals of very different colors. Tourmaline is most commonly found in Brazil and is also mined in Afghanistan, Pakistan, Kenya, Madagascar and Mozambique. IGS notes superb blue elbaite from Nuristan, Afghanistan, and Mindat records indicolite from many localities, including Nuristan, Namibia and South Dakota, USA.

IGS uses indicolite for blue tourmaline whose color is not caused by copper; intense neon-blue copper-bearing stones are classed as Paraíba tourmaline. Tourmaline is doubly refractive and pleochroic, and the color seen along the length of a crystal is consistently deeper than across it. Heating to lighten blue and green stones is common, stable and undetectable. IGS calls names such as "Brazilian sapphire" for blue tourmaline unacceptable, and notes that no lab-grown tourmaline is commercially available for jewelry.

GIA rates tourmaline 7 to 7.5 on the Mohs scale with fair toughness. It is generally stable to light and is not affected by chemicals, but high heat can change its color and sudden temperature changes can make it fracture. Colors produced by irradiation can fade with heat or bright light. Clean it with warm, soapy water; ultrasonic and steam cleaners are not recommended.

The name tourmaline comes from the Sinhalese toramalli, a term Dutch merchants applied to multicolored water-worn pebbles from the gem gravels of Sri Lanka. Until modern mineralogy, tourmaline was identified as other stones according to its color, and it was recognized as a distinct mineral species only in the 1800s. Mindat derives indicolite from the Latin indicum, "indigo" or "blue", and the Greek lithos, "stone".

According to GIA, ancient mystics believed tourmaline could inspire artistic expression because of its wide range of colors.

Tourmaline is listed as a birthstone for October, alongside opal, and as the gem of the eighth wedding anniversary.