Is there a way to approximately determine a hone's grit size if there are no markings on it?

I have an old barber's hone that I'd like to use. It's ceramic, I think.

Can you just feel it and compare it to the feel of the Norton or Japanese water stones?

I've seen some mention of slow-cutting stones vs. "efficient" stones. Could a finer hone feel coarser for some reason?