Kimberlite and of those just over 30 have been economic enough to diamond mine. The deposits occurring at Kimberley, South Africa, were the first recognized and the source of the name. The Kimberley diamonds were originally found in weathered kimberlite, which was colored yellow by limonite, and so was called "yellow ground". Deeper workings encountered less altered rock, serpentinized kimberlite, which miners call "blue ground". See also Mir Mine and Udachnaya pipe, both in the Sakha Republic, Siberia. The blue and yellow ground were both prolific producers of diamonds. After the yellow ground had been exhausted, miners in the late 19th
Gemstone irradiation Gemstone irradiation The gemstone irradiation is a process in which a gemstone is artificially irradiated 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. As a result, the gemstone's color may be significantly altered or the visibility of its inclusions may be lessened. The process, widely practised in jewelry industry, 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. Irradiation has