If your talking japanese synthetic hones like the Kitayama yes they are stamped on the honing surface and this is slowly removed as you use it. if you mean natural hones the contain several small stamps always on the side and they are intended to always be there. from what I gather they denote the type of hone, the quality, grade, sub grade and all that.

Also natural stones really don't soak up water at all like artificial hones do. The Coticules, eschers and japanese are all the same in this way. The rock is not a porous type. They certainly differ with the japanese probably being the most porous.