Again, actual grit size is irrelevant, so comparison based on micron size isn't really straightforward, especially since the grain size is only one of a multitude of factors that impact the resulting edge finish. But the finish produced with the as-fired surface finish of the stone is a bright mirror. You can consider it similar to a Spyderco Ultrafine or finer. The issue here is you're asking an apples question when we're dealing with oranges, if that makes sense. I realize you're looking for info that can help you figure out where it fits in a progression, but all I can tell you is that it produces a bright mirror finish. I can try taking a piece of steel, mirror polishing it, and then rubbing it on the plate to show the finish, though. I'll just need to find something appropriately hard since that does matter in polishing work. I think I have some appropriate scrap, though.