AGATES FROM AROUND THE WORLD - 1 lb. of rough agate rocks are sourced from around the world. Colors and sizes will vary between refill kits. FOUR GRADES OF GRIT - Coarse, Medium, Fine, Polish. Transform your raw stones from rough rocks to dazzling gemstones! This refill kit also works with all rock tumblers. JEWELRY FASTENINGS - Additional rock tumbler accessories include 1 Necklace, 1 set of Earrings, 1 Keychain, 1 Ring. Create custom jewelry from your newly polished gemstones! LEARNING GUIDE - Our detailed learning guide will teach you all about agates and includes many amazing and fascinating facts RESPECTED QUALITY - National Geographic is proud to provide only the highest quality STEM toys and all our kits are backed by our 100% satisfaction guarantee