You can also use a technique that involves sanding the rock with sandpaper, while slowly introducing higher grit levels. The starting level of your grit will vary depending on what type of rock you are working on. For a cut slab of rock you would start with 100 grit and move up to 320, then 400, and finish at 600. As for rough stone you would begin with a grit of 50, and cycle through the same grit levels listed above. You can continue polishing the rocks with a cloth or coat them with mineral oil or commercial rock polish. These polishes can be purchased online for a low cost.