Semi-precious tumblestones
A tumbled-polished gemstone is one that has been smoothed and polished to a high gloss by slowly grinding the stones against each other in barrel-like tumblers. Depending on the stone type, and the skill of the person managing the process, it may take anything from a few days to several weeks to achieve the desired result. Although the tumbling process remains a fairly "mechanical" process, there is a great deal of skill involved in obtaining the desired "polish" to the different stone types. However the basic process is one of using a grinding paste of Silicon Carbide Abrasive Powder and water to grind the stones to shape followed by a final tumbling with a polishing powder.