Hi. I'm curious about the grit designation of various sharpening stones. I have a Norton 1000,4000,8000. I also have a shiageto 1500 and 600 benchstone. The shiageto 600 is probably smoother and the 1500 is definitely smoother than the Norton 8000. At least that's how it feels to me. The shiagetos feel almost like porcelain. I don't use the the shiagetos, but I was just curious if anyone could explain this to me. Are these sharpening stones not comparable? Can these be used for straight razors.