The Gatco Diamond Sharpening Hone is a high quality diamond stone that works with any of the GATCO sharpening systems. Diamond cuts faster and does not require the use of honing oil. Choose between the fine, medium and coarse knife sharpening stones. The fine knife sharpening stone for putting a fine edge back on the blade. The medium knife sharpening stone is used for putting an edge back on the blade. The coarse knife sharpening stone is used for reshaping a very dull edge.