Spyderco ceramic sharpening stones are made of "High Alumina Ceramic," a USA made material with the ability to cut any metal known to man. It is formed when alumina particles (synthetic sapphires - only diamonds are harder) are mixed with a ceramic bonding agent. The mixture is then shaped and kiln-fired at temperatures is excess of 3000 degrees for up to three days.

The advantage that these ceramic stones have over diamond stones is that the ceramic sharpening stone has the full surface of the stone to sharpen and most diamond "stones" have a pattern of diamond coated dots.  This results in ceramic sharpening stones working faster. 

These ceramic sharpening stones are available in three grits - medium (600 grit), fine (1800 grit) and ultra-fine (2000 grit). Each grit serves a specific purpose in the sharpening process. The medium stone produces a good working edge by efficiently removing steel and reshaping bevel of a dull tool. The fine grit stone then tightens the scratch pattern - creating the desired razor sharp cutting edge. The ultra-fine stone then polishes the edge to provide a professionally finished edge. - No stropping is required.

Spyderco ceramic sharpening stones are to be used dry - no honing oil or water. Cleaning can be accomplished with a powered abrasive cleaner (Comet, Bon Ami, etc.) and a nylon or non-metallic scouring pad.