That will be dependent on the type of stone and the intended use.When buying a new stone. What goes through your mind when trying them and testing them? I hope that isn’t a hard general question that is impossible to answer. Thanks JPO
I have my preference with respect to how the stone feels in use.
I like really hard stones with what I call good traction and good honing sensation. You need to figure out what you like.
I also use magnification to get an idea of how they cut the steel.
I also rely on the testing done by the vendor. He is the expert.