Gemstone Adventures expands the Gemstone Fantasy Miniature System to include rules for guiding adventuring parties into monster-haunted dungeons in search of fame and fortune. The supplement describes 10 new hero types, 10 sample villains, 17 sample adventuring parties, 23 new spells and prayers, five new scenarios, new terrain rules for doors and treasure chests, advice on setting up and using a dungeon environment in Gemstone, and rules for building campaigns and advancing heroes. The book comes with a cut-apart insert containing 96 encounter cards and 140 treasure and other counters.