How does a diamond terminate its covalent network? Every reference I can find to the structure of diamonds merely shows the internal structure of the covalent network, but never the termination at the surface of the diamond. I would assume that it is with multiple bonds between some of the carbon atoms (mainly because that is the only decent answer of which I can think), but am unsure.
How does any object terminate at the surface? I assume that the ends just stick out. At this miniature level I suppose it doesn’t matter that the ends stick out. I am pretty sure that multiple bonds do not occur, because it would take too much energy to make these bonds and if they occurred naturally at the surface, they would occur naturally elsewhere (inside) and a diamond would cease to be a diamond.
Bonds at a material’s interface strive to be satisfied. Most often that is accomplished by bonding with whatever is around. Since water is everywhere most dangling bonds attract hydrogen, oxygen or hydroxyls(depending on its valence). Unlike rust, however, the hydrophilic and nucleophilic attacks do not continue past the surface of the diamond. The covalent carbon bonds are much too strong for that. You end up with a single atomic layer of an electrically satisfying terminator on the surface…too small to see, or to distract from the beauty of the gem.
No magic here, just math.
I think there is a one-atom layer of oxygen bonded to the carbon. This may or may not be the same thing TheBori said.
Remember that by definition, the interface of any materials is a fault and is considered a defect with respect to the bulk solid(s). The surface of diamond is unlikely to be flat (at an atomic level) and will rearrange to try to minimise the ‘unfavourableness’ of being sub-valent. By necessity, not all atoms will be sated, and this is the essence of surface science, and explains why so often catalytic processes are phenomena observed at surfaces. I don’t remember oxide formation being known at diamond surfaces (at STP), but could be wrong. I’ll look into it.
And does it make a difference that the diamond is not in its naturally occuring state, but rather a “cut and polished” stone? Just throwing this in as a question. I have no help for the OP.