I have been wondernig the same thing. Right now I have the diamond set (Course, Medium, Fine) and they have great for me. I was recently searching to try to find this answer and I read somewhere (cant remember where) that the blue saphire hone wasnt very quality. Some of the reviews I have read say that the surface is wavy and not flat. I seem to remember reading that the ultra fine (white) hone was 2000 grit and the super saphire (blue) is 2200? I could be wrong though, this is just what I remember reading. I would also be interested in hearing the comparison between the two.