This was discussed on the first page of this thread. The edges are beveled and as @Psypher1000 says above, all china clay sets I've handled have had beveled edges. @BGinGA pointed out earlier why it is unlikely that any china clay set will be produced with sharp edges.
Just bought a set of sprint mold china clays. As the first set I bought when they were first released, these chips have sharp, square edges.
I like them.
Too bad this idea is coming up now. I would have been in for some as I love the spots on the Dunes Commem's. (as well as Pharaoh's) but again, I just bought a set of sprint mold chips.