Editing Tourmaline (section)

=== Treatments ===
Some tourmaline gems, especially pink to red colored stones, are altered by [[heat treatment]] to improve their color. Overly dark red stones can be lightened by careful heat treatment. The pink color in manganese-containing near-colorless to pale pink stones can be greatly increased by irradiation with gamma-rays or electron beams. Irradiation is almost impossible to detect in tourmalines, and does not, currently, affect the value. Heavily included tourmalines, such as rubellite and Brazilian paraiba, are sometimes clarity-enhanced. A clarity-enhanced tourmaline (especially the paraiba variety) is worth much less than an untreated gem of equal clarity.<ref>Kurt Nassau (1984), ''Gemstone Enhancement: Heat, Irradiation, Impregnation, Dyeing, and Other Treatments'', Butterworth Publishers</ref>