The surface of a diamond

[big314mp]

Diamonds are a lattice of carbon atoms, each bonded to four other carbons. This leads me to two questions:

 

First, what happens at the surface of a diamond? How would the carbon atoms at the surface of a diamond bond?

 

Second, when a diamond breaks, carbon-carbon bonds have to be broken (assuming it doesn't break along an internal fault). This seems like it would be virtually impossible to do, and it also raises the question of what happens once these bonds are broken.

[hermanntrude]

I think the extra carbons at the surface are hydogenated. I think you're right that breaking a crystal requires breaking a C-C bond but evidently it's not impossible, since people do it, and I guess the newly-exposed carbon atoms must then become hydrogenated too.... perhaps they form bonds with atmospheric oxygen, though...

[big314mp]

Well, when a diamond grinder (the guy who shapes gem) is grinding the diamond, he must be breaking lots carbon-carbon bonds, that are then reforming rather rapidly with something else. It would seem that this would lead to unpredictable reactions at the surface of the diamond, possibly impacting the color/hardness/etc characteristics at the cut face.

 

And yet the cut face looks just like any other face of the diamond.

[insane_alien]

remember, the surface layer is only going to be a few angstroms thick, this isn't going to cause major structural damage, and isn't going to affect the colour noticably as there simply isn't sufficient density.

 

impurities from formation have more of an effect on colour and hardness than anything happening at the surface.

[big314mp]

You would think that it would have SOME effect though...

 

Perhaps it bonds with adjacent surface carbons via highly strained bonds?

[insane_alien]

well, you seem to be under the assumption that they must bond immediately. this is not so, the carbon atoms will hapily sit in a radicalised form until something to react with bumps into them. seeing as its usually done in air, oxygen is the most likely thing for it to bond to.

[big314mp]

http://t14web.lanl.gov/Research/TDAC2000/shaw.00.pdf

 

Searching on google for a while gave the above research, which seems to suggest that they do in fact bond to stuff in the air.

 

Thanks!