So back in the day I had a 3K/8K combo stone separate on me and crack about half way down.
I ultimately bought a new one, but I made use of the peices for travel.
Attachment 292339
Underneath, I glued a couple of diamond “stones.”
Attachment 292340
This ultimately gave me two “stones” with 4 grits. 600, 1,200, 3,000, and 8,000.
They certainly work in a pinch, but I find myself doing weird things to knives with them more often than not. And by weird I mean putting on a 8K edge on a knife might be overkill lol..