Color Types for Tourmaline
A brief description of the color types for Tourmaline used
Tourmaline is a crystalline boron silicate mineral compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is classified as a semi-preciousstone and the gemstone comes in a wide variety of colors.
Some tourmaline gems, especially pink to red colored stones, are altered by heat treatment to improve their color. Overly dark red stones can be lightened by careful heat treatment. The pink color in manganese-containing near-colorless to pale pink stones can be greatly increased by irradiation with gamma-rays or electron beams. Irradiation is almost impossible to detect in tourmalines, and does not, currently, impact the value.
Gem and specimen tourmaline is mined chiefly in Brazil and Africa. Some placer material suitable for gem use comes from Sri Lanka. In addition to Brazil, tourmaline is mined in Tanzania, Nigeria, Kenya, Madagascar, Mozambique, Namibia, Afghanistan, Pakistan, Sri- Lanka, and Malawi.
Cat’s eye Tourmaline
Color Types for Paraiba
A brief description of the color types for Paraiba used at Agl Thai Laboratory Gemology.
From "Paraíba", the state in Brazil in which the stone was discovered.
Paraíba tourmalines appear in a range of greenish blue, bluish green, green, blue, and violet hues. This gemstone is both the most precious and valuable in the world, and with one glance, it is easy to see just why. Glowing from the inside out. Paraiba Tourmaline is considered to be one of two different birthstones that can be accepted for the month of October and because of this, it is also one of the gemstones for Libras and Scorpios. It does tend to vary in color, like most Tourmaline, but its brilliance and somewhat neon glow comes from that fact that it contains the element Copper.