When I refer to manmade I refer to anything that's manmade.
I have a 12k water stone that is so old it came with a wooden base and I never tried it once with razors.
I only sharpened on it a few times. I tend not to sharpen blades on fine manmade water stones
They really seem to force you to strop other wise the edge doesn't seem sharp when feeling with the fingers.
The finest manmade I use is my shun 6k or king what ever grit the yellow one is not sure bought my two used
then I got natural.