Originally Posted by
mainaman
Just a clarification Nagura is the name of the stone it comes from Mikawa mine, from different seams which vary in fineness. The most popular ones are Botan (~ 8k) Mejiro (~15k) Koma (~20k and very rare).
Nagura does not speed up honing, its just another way to create progression for honing, using several different grades of Nagura stones on one finisher as a base. The final polishing job is done with the polishing stone itself.
You can use a piece of the same stone cut from it it is called Tomonagura, problem is one has to have the tools to cut their own stone and I am not sure people are willing to put an expensive stone to the saw.
Another way of creating slurry is to use a piece of another polishing stone called Honzan.
As far as nagura and stone compatibility you need your stone to be harder than the nagura, which should be the case with any Japanese natural razor hone.