• Polishing reveals a rock's hidden beautyrocks-smooth image by Jeffrey Zalesny from Fotolia.com
  
  Turn a handful of dirty rocks into a pile of gleaming, jewel-like stones through the art of rock tumbling. Maybe you want to polish rocks for jewelry or for display purposes. Whatever the reason, before you begin it's best to learn the basic requirements and procedures, so you don't end up ruining your rock collection or any of the equipment you paid for.
  
  

Tumblers

• A tumbler is a machine that speeds up the polishing process, turning on an axis so the chosen rocks spin through water and polishing materials at high speed and leaves them with a rounded shape. Some tumblers come with two or more barrels so you can have several batches of rocks being polished at the same time. A variation of the traditional rotating tumbler is a vibrating tumbler, which, according to the Rockpick Legend Co., smooths rocks while retaining their original shape, as opposed to rounding them.
  
  

Rocks

• Choose your rocks carefully and inspect them before beginning the polishing process. Try to keep rocks grouped according to similar sizes and weight. You can use rocks you got off the side of the road, or those purchased from a science or craft store. Avoid loading cracked or incredibly sharp rocks in the tumbler, as they can interfere with the process, warns Aussie Sapphire.com. Pick rocks that aren't porous and won't crumble easily.
  
  

Grit

• It's not just the tumbling motion that polishes the rocks, but also what you put in with them as they spin. Grit speeds up the polishing by grinding down the rock's sharp edges. It comes in various levels of coarseness. Often, depending on how polished you want the rocks to end up, you will go through at least three stages of grit, each smoothing out the scratches left by the previous stage.
  
  

Polish

• Once the rocks have been ground to a suitable smoothness, it's time for the final step. Adding polish to the tumbler gives the rocks a lovely shine and slick feeling. The most common types of polish are aluminum oxide, tin oxide and cerium oxide. Certain types of rocks react differently to polishes, so some experimentation is necessary.
  
  

Setup

• Take your chosen rocks and fill the tumbler's barrel so it is at least halfway full--at most three-quarters full. Fill the barrel with water until it touches the bottom of the top layer of rocks. Add your first stage of grit (about 2 to 3 tbsp). Then seal and activate the tumbler, and prepare to wait. It normally takes at least a week for each stage of grit and polish to complete.