Thread: What is Grit in Japanese Natural Stones, and How Important Is It.

I don't think that the "slurry pictures under a microscope" shows us the grit of a stone. They are pieces of abrasive glued or whatever it is called with pieces of the binding material. I don't think those pieces are actually the grit of the stone. Maybe if you take an X ray after, with this slurry, again under a microscope, we can have a better understanding (if the abrasive and the binder have different density). A good way to find out which stone is finer, by my opinion, would be to polish or burnish its surface to the highest degree(not with diamond since it will abrade out abrasive particles), and then take a look of how fine its surface looks under high magnification. You will not be able to see the whole size of the particles, but the size and shape of edges on the surface, compared to others, might be helpful.