These GATCO Diamond Sharpening Hones are a direct replacement for your GATCO Knife Sharpening Systems. Whether you need to add to your set or replace an old stone, these stones are perfectly matched for any of the GATCO Systems using the Knife Clamp Guide System. Coarse Diamond: Orange Color, Provides fast resharpening of all knives and damaged blades Medium Diamond: Dark Green Color, Maintains keen edge on all knives Fine Diamond: Pink Color, Provides polished edge in final sharpening