Cally Oldershaw is a geologist and gemmologist. She is the author of 15 books on gemstones, and Earth science topics including volcanoes, earthquakes, and oceans and seas. Cally has appeared on television and radio and was the Curator of Gemstones for the Natural History Museum, London and the first Lady Chair of the Gemmological Association of Great Britain. She studied at University College, London and has been a guest lecturer for the universities of Oxford, Cambridge, and London.