I haven't done it myself, but I was just throwing a few dishes in there when I looked at my (formerly) yellow and white stone, which doesn't look anything like it did when I bought it a couple of years ago. It's all gray from metal particles and grit that have embedded themselves on the white side.

Maybe the dishwasher wouldn't do much aside from get soap in there or something.

Aside from a small and smooth barber hone of mine, it's my only stone, and I understand people lap theirs from time to time with other ones. Is that why when I see people's stones in YouTube videos, they've managed to maintain that canvas-white / canary-yellow look?

Pumice -- isn't that the other thing? How do I ensure that I don't warp the thing somehow? I think I remember reading about people laying them on glass or something. Is that a surefire way?