From: Ed Minch wrote: "how do I tell which side is the finer stone?? ?  in fact,
how do you guess the grit of any stone you night find?"

Make sure it is clean, then use it a bit. The coarser side will feel raspier,
and you may--- should--- be able to see the different size of the scratch
patterns under moderate magnification (say 10X to 30X). It can be tricky
comparing two completely different stones (for instance, one may have smaller
but sharper grains than the other), but the two sides of one stone shouldn't be
difficult. Don't get hung up on grit size; the hardness and geometry of the
grains are at least as important.
Tom Conroy