The bottom line is using AO I and many others get hair splitting and beyond edges on S30V. M2 has 2% Vanadium, and M4 has 4% Vanadium, identical to S30V, and not many people complain about M4 being hard to sharpen on ceramics. I have trouble with all hard M2 on ceramics, but that is because it is 65 RC (I have similar issues with other super hard steels with little Vanadium on ceramics). Maybe diamonds are ideal, but I have found a 1 micron diamond edge to have a toothier feeling to it than a 1 micron AO finish, probably due to the shape of the abrasive. When you look at my .05 micron edges at 100x there is nothing toothy about it. After using it S30V definately dulls to a rougher edge much faster than ZDP 189 or M4, but it still keeps cutting OK because those carbides are in there to allow the edge to keep cutting while the knife is pretty dull. I have read about the carbides falling out as you continue to cut, which allows you to keep cutting while the edge is dull with the edge kind of self sharpening by exposing new carbides as the others fall out. I can't stand to cut with a knife once it reaches that level, but most people who don't sharpen have commented on how sharp a blade was after I stopped using it and pulled out another, probably because they haven't handled a sharp knife and are used to cutting with knives that are spoon dull. I just have a certain level of sharpness that I like to have, and steels like Super Blue, ZDP-189, and M4 (also a AEB-L knife hardened to 62-63 RC) maintain a very high level of sharpness a long time, where steels like S30V lose their extreme sharpness much faster. Anyway, back to the original point I think there are enough people out there that get hair splitting edges from S30V with non diamond stones to prove that you don't need diamonds to reach extreme sharpness. Seeing micrographs would be really nice, but in terms of real world performance the ceramics and waterstones and AO lapping film get S30V just as sharp as diamonds.
Mike
