Gemstone irradiation produce mixtures of blue and yellow-to-brown colors, so heating is required as an additional procedure to remove the yellowish color. In some cases, the new colors induced by artificial irradiation may fade rapidly when exposed to light or gentle heat, so some laboratories submit them to a "fade test" to determine color stability. Sometimes colorless or pink beryls become deep blue upon irradiation, which are called Maxixe-type beryl. However, the color easily fades when exposed to heat or light, so it has no practical jewelry application. Gemstone irradiation The gemstone irradiation is a process in which a gemstone is artificially
USS Aquamarine (PYc-7) named for the gemstone aquamarine. Assigned to the Naval Research Laboratory, Bellevue, D.C., "Aquamarine" assisted in experimental work, chiefly underwater sound. Although most of her experiments were conducted on the Potomac River and Chesapeake Bay, she also operated off New London, Connecticut, from 16 October to 4 November 1943, and off the Florida coast and in the Bahamas from 24 January 1944 to 18 April 1945. During 1945 and 1946 "Aquamarine" had additional duty as special tender to the presidential yachts and . "Aquamarine" was decommissioned on 21 June 1946 and transferred to the Maritime Commission on 31 January 1947