Having nice, shiny "gems" made from your personal rock collection takes time, as well as the right supplies. Using a rock tumbler is not a craft for those who are short on patience. However, it can be a fun and satisfying hobby for mineral enthusiasts.
First, it is necessary to choose the right rocks and minerals to tumble! Soft rocks like sandstone and limestone will only be crushed to dust. Even harder materials like granite will significantly decrease in size, so don't start with a pebble much small than a quarter. If you do, you will end up with something so tiny you may not be able to find it in the sludge.
Next, make sure you have a good location for your rock tumbler. Keep in mind that this thing will be going nonstop for several weeks! If the sound of slurshing rocks and sand bothers you, you may not want it in the room where you will be spending a lot of time. The basement or laundry room is a good location for keeping your rock tumbler. Also, in case of leaks, make sure you have it set on some plastic or inside a plastic tub.
Throughout the process, you will want to examine your rock tumbler to make sure it is not leaking. If it is, you may simply not have it sealed tightly enough. Make sure that no stones or grit have compromised the rubber seal.
Rock tumbling kits come with several different grades of grit. The rocks will first be tumbled with gravel, which will wear away the sharp edges. After a week or two, you can take the lid off your tumbler and check on your rocks. If they look a bit rounded, it is now time to move along to the course sand that will wear them down even more.
After a week or two with the course sand, you will repeat the process with at least two more grades of increasingly fine sand. When changing grit, make sure the wash the rocks thoroughly. They will not get polished well if the old, course, grit is still hanging around!
Finally, some smooth plastic beads are used to give the rocks a brilliant shine. You can now use them as accents in jewelry or crafts, or as an added touch of style for a potted plant. If you have access to a lapidary drill, you can cut holes in them, and if you can use a lapidary saw, you can make flat-bottomed stones for use in bracelets or belt buckles. However, even if you have no specialized equipment besides your rock tumbler, you can still use glue or wire-wrapping to turn your rocks into wearable art.