Zomax,

I have no 'hard' stones, so I have no experience of how the DMT would fare with these.

However, I use my DMT325 for my 4/8 k Norton and my 1, 3, 5, 8, 10 & 12k Naniwa SuperStones with excellent results

The DMT is so much easier and cleaner to use than carbide paper on glass !

Have fun !

Best regards

Russ