light to strong pink, orangy red, red, purplish red, purple, inky blue, blue, bluish violet, violet, greenish blue, light to dark green-blue to yellowish green, dark green, yellow, orange, brown, dark brown, black and rarely colorless
achroite, bi-color or parti-colored, chrome tourmaline, dravite, elbaite, fluor-buergerite, indicolite, liddicoatite, povondtaite, paraba tourmaline, rubellite, schorl, uvite, verdelite, watermelon
appearance, refractive index and high birefringence; then optic figure, pleochroism and specific gravity
Crystal habit is prismatic and may be 3, 6 or 9-sided; often a triangular prism with convex faces, and often long and heavily striated parallel to the c axis. Pyramidal terminations are common.Misnomers: Brazilian sapphire-blue tourmaline; Brazilian emerald, Ceylonese peridot-green tourmaline.Achroite: colorlessBi-color or parti-colored: tourmaline with two colors and multiple colorsChrome tourmaline: fine intense green usually colored by chrome or vanadium Dravite: yellow or brown tourmalineElbaite: a sodium lithium aluminum tourmaline speciesFluor-buergerite: bronzish-brown to dark-brown to almost black with bronze schillerIndicolite or indigolite: violetish blue to greenish blueLiddicoatite: a calcium lithium tourmaline speciesPovondtaite: dark brown, brownish black to black with resinous lusterParaba tourmaline: a neon blue to green colored cuprian Elbaite tourmaline originally found in the Brazilian State of ParaibaRubellite: deep pink to red stonesSchorl: black, brownish black or blueish black stonesUvite: a calcium magnesium aluminum tourmaline speciesVerdelite: dark green,yellowish green, brownish green to blueish greenWatermelon: pink center with green edgesBirefringence is typically around 0.020 but dark material can be up to 0.040 October birthstonePyroelectric: development of opposite charges at the ends of a tourmaline crystal due to change in temperature. Piezoelectric: development of opposite charges at the ends of a tourmaline crystal when placed under stress.