Spyderco Ceramic Stones. Spyderco sharpening tools are made of "High Alumina Cermic", a U.S.A made material with the ability to cut any metal known to man. It is formed when alumina particles (synthetic sapphries) are mixed with a ceramic bonding agent. The mixture is shaped and kiln fired at temperatures in excess of 3000°F for up to three days.
Spyderco ceramics come in three grits - medium, fine and ultra fine - none of which requires lubricants such as oil or water for use. Each grit serves a different purpose in the shapening process. The medium grit stone products a good working edge by efficiently removing steel and reshaping he bevel of a dull cutting tool. The fin grit stone then tightens the scratch pattern, creating a razor-sharp edge. The fine and ultra-fine grit stones are "close celled" (the particles that make them up are very dense) and will show little or no wear over time. The medium grit stones are "open-celled" (particles are less dense) and will wear only slightly over time.