Rock tumbling for beginners: the real grit progression that works

Rotary tumbling is a multi stage process and skipping steps or rushing them is the most common reason beginners end up with dull or pitted stones. Stage one uses a coarse grit, typically 60 or 90 grit silicon carbide, and is meant to round the stones and knock off any sharp edges, usually running 7 to 14 days depending on how rough the starting material is. Stage two moves to a medium grit, commonly 150 or 220, run for about 5 to 7 days, and its whole job is removing the larger pits left behind by stage one. Stage three is a fine pre polish grit, often 500, again roughly 5 to 7 days, which removes the finer scratches left by stage two. Stage four is the actual polish, using a polishing agent like cerium oxide, tin oxide, or aluminum oxide, typically another 5 to 7 days. The single most important habit between every stage is thoroughly washing the barrel, the lid, and every stone before moving to the next grit, even a few leftover coarse grains carried into a finer stage will scratch every stone in that batch and ruin the final polish. Fill the barrel roughly two thirds to three quarters full including the stones for the best tumbling action.