Gemstone irradiation

A B B B C C Pure diamonds, before and after irradiation treatment A Initial (2×2 mm size) B Irradiated by different doses of 2 MeV electrons C Irradiated by different doses and then annealed at 800 °C (1,470 °F)

Gemstone irradiation is a process in which a gemstone is exposed to artificial radiation in order to enhance its optical properties. High levels of ionizing radiation can change the atomic structure of the gemstone's crystal lattice, which in turn alters the optical properties within it.^[1] As a result, the gem­stone's color may be significantly altered or the visibility of its inclusions may be lessened.

The process, widely practiced in jewelry industry,^[2] is done in either a nuclear reactor for neutron bombardment, a particle accelerator for electron bombard­ment, or a gamma ray facility using the radioactive isotope cobalt-60.^[1][3] The irradiation treatment has enabled the creation of gemstone colors that do not exist or are extremely rare in nature.^[1] However, the process, particularly when done in a nuclear reactor, can make the gemstones radioactive. Health risks related to the residual radioactivity in the irradiated gemstones have led to government regulations in many countries.