Gem: The Definitive Visual Guide

DK was founded in London in 1974 and is now the world's leading illustrated reference publisher and part of Penguin Random House, formed on July 1, 2013. DK publishes highly visual, photographic nonfiction for adults and children. DK produces content for consumers in over 87 countries and in 62 languages, with offices in Delhi, London, Melbourne, Munich, New York, and Toronto. DK's aim is to inform, enrich, and entertain readers of all ages, and everything DK publishes, whether print or digital, embodies the unique DK design approach. DK brings unrivalled clarity to a wide range of topics with a unique combination of words and pictures, put together to spectacular effect. We have a reputation for innovation in design for both print and digital products.   Our adult range spans travel, including the award-winning DK Eyewitness Travel Guides, history, science, nature, sport, gardening, cookery, and parenting. DK’s extensive children’s list showcases a fantastic store of information for children, toddlers, and babies. DK covers everything from animals and the human body, to homework help and craft activities, together with an impressive list of licensing titles, including the bestselling LEGO® books. DK acts as the parent company for Alpha Books, publisher of the Idiot's Guides series and Prima Games, video gaming publishers, as well as the award-winning travel publisher, Rough Guides.

Aja Raden is a scientist, jeweler, writer, and historian. She was educated at the University of Chicago in the subject of ancient history. Raden is the author of Gem and Stoned: Jewelry, Obsession, and How Desire Shapes the World. Before embarking on her writing career, Raden was the senior designer for the jewelry company Tacori. You can follow her at @AjaRaden.