books.google.co.uk - A guide to the fascinating world of precious crystals, naturally-occurring minerals, 'organic gems' and synthetic gems and simulants. An introductory section examines the appeal of gemstones, the history and popularity of collecting, the basic rock types, principles of crystal formation and physical...http://books.google.co.uk/books/about/Gemstones.html?id=MPZK8ILOSR0C&utm_source=gb-gplus-shareGemstones
