Oilstones, also known as sharpening stones, are tools used to sharpen and hone the edges of blades and tools. They are typically made from materials like aluminum oxide, silicon carbide, or natural stones. The surface of an oilstone is lubricated with oil, which helps to reduce friction and carry away metal filings during the sharpening process. These stones come in various grits, ranging from coarse to fine, allowing users to achieve different levels of sharpness. Proper use of oilstones can extend the life of tools such as knives, chisels, and saws, making them essential for both professional and hobbyist craftsmen.