A sharpening stone is the easiest way to return your knives and other cutlery to a useful state once they begin to dull. Not only knives but also scissors, razors, chisels, and plane blades can be sharpened with a stone. Sharpening stones are made of very hard stone or a manufactured material, such as ceramic or diamond stone. Usually in the form of a block that you hold in your hand or set on a flat surface, although they can also be found in the form of bench stones, wheels, or rods, these blocks are also called whetstones or waterstones.

Most stones are assigned a grit size; the finer the grit, the finer the grinding ability. Some sharpening stones are fine on one side and coarse on the other. The coarser grits begin the sharpening process, while a finer grit sharpening stone is necessary to refine the blade.

When using a sharpening stone, there are three keys to success. First, ensure that you are leaving a controlled edge angle on the knife blade by using an angle guide. Second, make sure that you establish an entirely new edge by sharpening until you raise a burr on the steel. Third, make sure that the new edge is smooth by honing or polishing the blade.

Before using a sharpening stone to sharpen your knife, moisten it with water or oil. This moisture will absorb the metal and stone dust that will be created during the sharpening process. It also makes the stone more effective at sharpening the knife. Diamond stones sometimes have an interrupted surface covered with dozens of recessed dots that collects the removed metal swarf and keeps it out of the way as you sharpen your blade.

To use a sharpening stone, try to hold the knife as if you are trying to slice a very thin layer off the surface of the stone. One of the most important parts of using a knife sharpener is to maintain a consistent angle as you sharpen the blade of your knife. Many people accidentally lift the edge of the blade against the stone, creating too much of an angle between the blade and the stone. Over time, this will diminish the quality of the edge you are able to achieve. To correct this problem, you may want to use an angle guide when sharpening your knives to ensure a consistent angle.

While sharpening your knife, Place the blade across the stone, and tilt at the desired angle. For most kitchen cutlery, this is somewhere between 15 and 35 degrees. The optimum angle should be stated in any paperwork you have for your cutlery, but use 20 degrees if you are not certain. With your wrists held rigid, draw the blade against the stone. This grinding action will remove a thin layer of the blade. Periodically move the stone so that you are working on a different section of the blade. Ensure that the blade is sharpened to a point by rubbing the stone on each side of the blade until the tip of the blade reaches the desired sharpness.

When sharpening a knife using a sharpening stone, keep sharpening until enough steel has been removed to form a burr on the edge of the blade. This burr will be removed during the honing and polishing process, but it is the easiest way to ensure that you have removed enough metal, exposing a completely new knife edge. Once the knife is polished, it will be ready for use again.