i don't think many people would drop back from a 12k to a 6k , they may go from a 30k synthetic, in this case a shapton 30k. and then finsh with a natural stone . a natural stone tends to tame a very sharp edge , probably just like cronium oxide would. even a ch12k would probably work, i'm not to sure. may of us have used nortons for majority of the work, ten finished with a natural finisher to create a more forgiving softer edge , thats how it feels to me any way. i've shaved of 12k naniwa a couple of times and that is very close if not as good as a natural finisher. i'd never go back to a 6k after a 12k. naturals don't have grit rating, they just make a sharp nice edge a little more skin feindly in my opinion. same as cro .ox