I've now got a Chosera 1k and a Gokumyo 20 both of which came w prep stones. What are they for? The Gokumyo came w detailed instructions, unfortunately in Japanese. Has anyone translated them? The prep stone is 1 and 3k.

They are too small for flattening. I don't think they are intended to make slurry. Maybe just bring new grit to the surface? Maybe clear swarf? Maybe paperweights?

thanks in advance.