The Gemmological Association of Great Britain (Gem-A) is a non-profit making organization whose principal objectives are: the scientific study of gem materials; to establish education systems and hold examinations; to provide laboratory services to the jewellery trade; and to maintain libraries and collections of gem materials. There are three categories of Gem-A Membership. Courses in gemmology and diamond education are run worldwide, offered as both college-based and home study. Gems, books and instruments are available from the shop at the Gem-A in London, or via mail order.