I have used the TOS more than I have the Belgian blue. I find the TOS to be a very useful stone for the micrchip removal and for the "feel" of the edge that it develops. I always use a slurry with the TOS and usually follow it with the Norton 8K and Escher then the 0.5 micron chrome oxide. It gives me an edge that I really like. To me the TOS is finer than the blue but of course each blue is a bit different. YMMV.