Better yet

Take three or four 8k Synthetics and use test blocks to check the Stria and you soon realize that the numbers stamped on Synthetic Hones only have real meaning between Hones of the same Brand and Series...


ie: A 8k Shapton GS is a finer Hone then a 4k Shapton GS

but

It may or may not be a finer grit then a 5k Naniwa SS,, or better yet compare a Naniwa SS 5k to the Naniwa 5k Professional and learn that the Binder and Type of grit can effect the Stria..

Now relate that to the millions of combinations that Mother Nature can use on her stones and you can understand the issue of assigning grit numbers to them