The "agate cutter" pics are hilarious. Can you imagine laying down on the job all day (literally).
A pic of some more non-glass marbles, I think a couple are actually ground stone rather than clay/ceramic, maybe a couple ivory or bone too. Plus a neat note that came with some agates as I got them. (7th grade in 1927 wasn't me) I never paid much attention to the non-glass marbles and didn't think I had so many until I started rooting around