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.

The reddish to purple color of tourmaline is called rubellite. Like emerald, inclusions are common. Ruby red colored stones are the most valuable.

Pink, red and purple tourmaline is occasionally heat treated to improve color.

More information on gemstone enhancements.

Rubellite is a member of the Tourmaline gemstone family.