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.

Long tourmaline crystals often form with different colored layers. Watermelon tourmaline is named by the slices which are formed when these crystals are cut. They have a pink center, sometimes surrounded by a colorless (white) layer and a green "rind". Watermelon and Bi-color tourmalines are normally quite included.

Occasionally heat treated to improve color.

More information on gemstone enhancements.

Watermelon Tourmaline is a member of the Tourmaline gemstone family.