General Tourmaline Overviews Streeter: Tourmaline Locations and Value Wodiska: 10 Pages on Tourmalines Feuchtwanger: Tourmalines (also origin of colors) Tourmaline Properties Electric Stones: Scientific studies of Tourmaline’s electrical properties. Catelle: “Tourmaline and other gemstones” USA Tourmaline (Maine, California, NY City) Maine Tourmaline Mining Bastin’s “Pegmatites in Maine“.A complete book on Maine’s Tourmalines !! George FrederickContinue reading »
Tourmaline Consumer Information
As provided and validated by various gemmological organizations, laboratories and the "World Jewelry Confederation CIBJO"
purplish. Verdelite – yellow green to bluish green. Indicolite – violetish to greenish blue. Dravite – yellow to brown tourmalines. One bright yellow variety has been called “canary tourmaline” in the trade. Paraiba tourmaline – eclectic, radiant, blue.
large clean tourmalines in the blue and blue-green colors are available, almost all red and pink tourmalines will show eye-visible inclusions. The most common inclusions in tourmaline are fractures and liquid-filled healed fractures. Needle inclusions are also common.
often resulting in very long, rectangular shapes. While tourmalines can be cut in all shapes and sizes, rectangular shapes predominate. Crystals often exhibit more than one colour; in such cases bi-colour or parti-colour gemstones result. On rare occasions, tourmalines are also carved.
colours from overly dark gems. In cuprian elbaites (paraiba tourmalines), heating causes some dark purple material to become strongly greenish blue or deep blue. There are some undesirable effects of heating: some pink and red tourmaline may fade to nearly colourless upon heating. Irradiation: This treatment was used to produce darker red gems from light pinks.
toothbrush. Collector gems: Paraiba tourmalines, particularly those from Paraiba, Brazil. Copper bearing gems from Mozambique and Nigeria: recent production has lagged at these sources. Strong color tourmalines from limited, high quality pockets. Bi-color and cat’s eye tourmalines.