Great way to start a rock collection! Learn about the exciting hobby of rock tumbling with National Geographic. This set includes all the accessories you’ll need to start polishing dazzling gems. Rock tumbling is tons of fun and a great way to start an extraordinary rock collection. Kids can use the included jewelry fastening to create beautiful homemade jewelry! High-quality tumbling machine with powerful motor that will last for years Automatic shutoff timer so you can set it and forget it Noise reducing leak-proof barrel with stainless steel lid Half pound of gemstones from around the world (9 types) and four grades of grit Jewelry fastenings so you can create your own unique jewelry Full-colour information guide with cool facts about each of the gemstones included Easy-to-follow rock tumbling instructions Imported/. Kids & Baby > Toys > Books & Learning Toys. National Geographic.