Heat and irradiation are common treatments used to improve the color of tourmaline. Both of these treatments are commonly done after the stones have been cut and polished. They can be undetectable when viewed with a gemological microscope.

Heat treatment can lighten an undesirable tone in some materials and give some brownish stones a brighter, more desirable color. The results of heat treatment are usually permanent. Stones with liquid inclusions are not good candidates for heat treatment because heating can cause them to fracture.

Irradiation treatment can brighten many light-colored stones. The results are often reversed if the stones are heated. They can also be reversed over time with exposure to bright light.