6 New Silicon Carbide Sharpening Stones. This is a new set of 6 silicon carbide sharpening stones. These are perfect for sharpening knives, scissors, gravers, etc. Each measures approximately 4" (101.6 mm) long. We work hard to update our descriptions and pictures of our merchandise. As part of a process of ongoing innovation by our suppliers, newer versions of the item shown may be shipped before we are able to complete an update. As a result there may be a slight variation in color and design.