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Too late. The King stone co. does that already with their 8k, ie add natural particles to the stone. Now my head's spinning. ;)

Glad my analogy was not wasted on you guys. :p

Rather than estimating a grit rating on a stone that has not been sifted thru a uniform mesh, just see where it fits in your progression.
There are...

I have this really bright coloured orange that'a almost red. I'm sure it could be an apple. :p ;)