Thames & Kosmos Rock TumblerThe Thames and Kosmos Rock Tumbler is a hands on kit that lets children transform rough rock specimens into beautifully polished gems. The kit comes with a selection of genuine rocks to get started, including amethyst, aventurine, and rose quartz, along with four types of polishing grit to work through the tumbling process step by step. Once polished, the included jewellery settings allow children to turn their specimens into their own unique