Unlike manufactured sharpening stones, Natural Stones are mined from particular mountains in Japan. They aren’t classified by grit, they’re measured by density. One way to control the grit of the Natural Stones is to use a Nagura Stone.
The Nagura will create a slurry on the surface of the Natural Stone. Depending on the Nagura Stone you use the slurry will be fine or coarse. This gives you entirely unique edge when you use them. Generally speaking Natural Stones give you better edge retention.
Natural Stones are rare, beautiful, and awesome. Their magic is hard to put into words. I can promise that when you use them, you’ll notice the difference.