The first section - 'The World of Gems' - contains information on gem formation, mining, crystal structure, and both the optical and physical properties of gemstones. The other useful topics include the diamond industry, fashioning and cutting, imitation and synthetic stones, and gem enhancement, as well as information on buying gemstones and diamonds, the history of gems, famous diamonds, and how to care for gems. A colour key is included to help identification, organized by broad colour ranges (yellow to brown, red to pink, blue to violet, green, colourless, white, black and iridescent). The second section - 'Gems of the World' - provides an in-depth description of each gem. Organized by chemical composition and grouped in a logical classification scheme, each gem has its own full-page or double-page entry. As well as the raw crystal, other photos and artworks show the preferred cuts and beautiful examples of jewellery made from the gem.The explanatory text provides information about the conditions under which the gem is formed, where it is mined and its physical properties. It also details the history and folklore attached to each gem, its significance as a jewel, key features to look for, and where the finest examples are found. Each entry is accompanied by a ready-reference fact box featuring key information about the gem, including its refractive index, relative density and hardness rating. A series of maps identify the most important gem locations in the world. Philip's Gems of the World will appeal both to students of gemology and to the thousands of buyers, dealers and collectors who need an accessible yet comprehensive guide to the world's gemstones.