8.0 on the Mohs scale.

Brazil, U.S., Sri Lanka (Ceylon), Myanmar (Burma), former USSR, Australia, Pakistan, Mexico, Tasmania, Japan, Africa. Topaz and citrine are the birthstones of the month of November.

Reddish, or peachy-orange in color. The term "imperial topaz" is used by ethical jewelers to refer to topaz that is reddish orange of medium tone and higher saturation.

Sometimes irradiated to intensify color.

More information on gemstone enhancements.

Imperial Topaz is a member of the Precious Topaz gemstone family.