Gemstone irradiation

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.

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.

The term irradiation broadly refers to the exposure of matter to subatomic particles or electromagnetic radiation across the entire spectrum, which includes—in order of increasing frequency and decreasing wavelength—infrared, visible light, ultraviolet, X-rays, and gamma rays.

[b] The first documented artificially irradiated gemstone was created by English chemist William Crookes in 1905 by burying a colorless diamond in powdered radium bromide.

[1] In the United States, the Nuclear Regulatory Commission (NRC) has set strict limits on the allowable levels of residual radioactivity before an irradiated gemstone can be distributed in the country.

[3] In India, the Board of Radiation and Isotope Technology (BRIT), the industrial unit of the Department of Atomic Energy, conducts the process for private sectors.

[27] According to the American Gem Trade Association, approximately 30 million carats (6,000 kg or 13,000 lb) of topaz are irradiated every year globally, 40 percent of which were done in the United States as of 1988.

[1] Quartz crystals turn "smoky" or light gray upon irradiation if they contain an aluminum impurity, or amethyst if small amounts of iron are present in them; either of the results can be obtained from natural radiation as well.