Oilstone is a type of sharpening stone used to sharpen tools and blades. It is made from a combination of aluminum oxide and silicon carbide, which makes it harder than other stones. The term 'HONE' is used to describe the process of sharpening with an oilstone. This involves rubbing the blade against the stone in a circular motion, using oil as a lubricant. This process helps to create a smooth, sharp edge on the blade.