What's On The Edge Of A Diamond?

I realise it's a crystal lattice, but the diagrams merely show the edges going on forever, how diamonds have fixed shapes, what happens at edges? Surely there aren't just carbon bonds floating around.

A diamond changing to graphite is merely a rearranging of their bond structure. This kinda thing happens precisely because of surface arrangements, and it doesn't happen just with diamonds, but any kind of macromolecule relying on a repetitive pattern.

I do molecular simulations of some of these crystals, and every time before we calculate collisions, etc, we "relax" the crystal. We know what the general "unit cell" of the crystal looks like, but not at all how it'll be arranged at the surfaces, so we let the system relax, each atom moving under the forces pushing it back and forth, and ultimately they form strange shapes; a rectangular crystal might become pseudo-circular at the boundary, or with more pinched edges, you never really know.

I can only speculate that with diamonds, given the ease of bonding of carbon atoms, there's a lot of contamination from environmental residue.