Hidden within the geological formations of our planet are some of the most unique and beautiful expressions of nature: fancy coloured diamonds. For centuries, these mysterious, exotic, and rare gemstones have been admired by connoisseurs, analyzed by gemologists, and coveted by collectors. Collecting and Classifying Coloured Diamonds, provides a detailed and handsomely illustrated account of these unusual gemstones. Using the Aurora Collection of 260 fancy colour diamonds as its foundation, Collecting and Classifying Coloured Diamonds, explores the gamut of colours displayed by diamonds in nature and, in a format for both the layperson and the expert, investigates how diamond colours are perceived, measured, and classified. The Aurora Collection, considered one of the finest in the world, has been on exhibit at the American Museum of Natural History in New York since 1989.