- Color: wide color range, green, blue, yellow, pink, red, brown, colorless. Bi-color is common.
- Hardness: 7 - 7.5
- Refractive index: 1.61 - 1.66
- Density: 3.01 - 3.25
- Chemical composition: (NaLiCa)(Fe11MgMnAl)3Al6((OH)4(BO3)3Si6O18)
- Crystal structure: trigonal
- Origins: Brazil, Madagascar, Namibia, Zambia, Sri Lanka, Burma, Russia, USA, Afghanistan.
Tourmalines exist in different colors and are known for their bi-color or even tri-color varieties. The most expensive color varieties are intense green, blue and red (see also the Tourmaline Paraiba and Tourmaline Rubelite sections). Heat treatment is occasionally applied to enhance the color of green or blue crystals. Yellow stones could be irradiated to improve their color or clarity.