5.5 - 6.5 on the Mohs scale.

Australia, former Czechoslovakia, U.S., Brazil, Mexico and southern Africa. Opal and tourmaline are the birthstones of the month of October.

Orangish yellow to dark red, usually with exceptional fire. These opal are cut en-cabochon along with the original rock they are found in (Matrix).

Mexican matrix opal is commonly treated with a sugar solution infilling in acid bath to darken the background and enhance color play and intensity.

More information on gemstone enhancements.

Mexican Matrix Opal is a member of the Opal gemstone family.