David Weaver
They're ceramic, probably not dissimilar vs. what's in a shapton, but the difference is my understanding is that the binder is ceramic, or the matrix is uniform - one or the other. They're not ceramic in a resin matrix or something designed to shed particles.

I tried them and recognized them to be similar to natural stones in that they become slower as they wear, but I prefer natural stones for finishing despite that.

They were, for a long time, made by coorstek (former ceramic company owned by or related to coors brewing, but with far more reach than brewing related support). Not sure if someone else is making them now, as I've seen coorstek sharpening stones.

Bill could clarify, but I'm not aware of too much difference between many of the ceramics used for structure and wear parts and perhaps a more closely graded particle sized slab being used for sharpening.

They do not wear much at all and the porous nature of the medium stones (Think bottom of a coffee cup where it's unglazed) makes them slow down and load. I believe george uses his medium after a diamond stone, then the fine, and then strops on a loaded strop.

All that said, I'd resign them to fine work if you find you like them, but I like oilstones better (even for V11) and would rather have 1 micron diamonds in an oilstone if giving said stone a difficult assignment.