7.0 on the Mohs scale.

Madagascar, North America, Brazil, Myanmar (Burma), Africa, Siberia, Australia, Sri Lanka (Ceylon). Tourmaline and opal are the birthstones of the month of October. Tourmaline is the national gemstone of the United States.

Tourmaline of different colors often form within the same crystal. These are can be quite varied in appearance.

Occasionally heat treated to improve color.

More information on gemstone enhancements.

Bi-color Tourmaline is a member of the Tourmaline gemstone family.