This edition of Geology of Gem Deposits, compiled by the Mineralogical Association of Canada, is a collection of technical papers accompanying the short course of the same name that was originally offered in Canada in 2007 and recently held in February 2014 during the gem shows in Tucson, Arizona. The quality of the papers is on the level of those found in scientific journals, addressing an audience knowledgeable about fundamental geologic principles and how they pertain to gem materials.