Received a Norton Crystolon coarse silicone carbide stone today in the mail. This stone is rated at 120 grit. Of course I had to try the stone so out came my M4 edc knife and I sharpened it back to a zero grind. This knife is not the easiest to sharpen as M4 has plenty of vanadium and this knife has a hardness of 62rc with a wider bevel as the grind angles are 8d/s, so lots of hard material to remove. I am happy with the stone as it seemed to work fairly fast and left a consistent scratch pattern that will be easy to refine. I think I am going to get a fine Crystolon stone to see how well it will refine the bevel scratch pattern. The Crystolon stone is probably a little slower than diamonds as the scratch pattern is more consistent and not as deep as a worn in black, 220, DMT stone. It will take some time to get a better feeling but as of now i am happy with the purchase.