Napolean, Ladiesman, A perfectly bonded Diamond is virtually inpenetrable. However, such thing doesn't exactly exist (save for over a few atoms). I can't exactly give a whole year 11 chem lesson on a messageboard, but it'snot really the most complex science.
If a diamond, or ANY element for that matter, is bonded 'unpurely', then it will have more chance of shattering or breaking. Coal, for example, is carbon, but poorly bonded. And it would make very poor armour
It only breaks along the planes because that is where the bonds are weak. Without any 'bad' bonds, it would be somewhat inpenetrable, the only thing making it unsuitable as a form of armour is what happens once it's heated
Stormin, what causes objects to seperate is not force, it's energy. Of course when two objects collide, you get heat. Hence, eating away at armour when you fire the guns used in science fictions.
Diamond would be a nice armour - except that it has virtually no melting point - it virtually goes straight to a gas. One moment you would have nice, hard, solid, thick armour... the next moment you would be armoured by a lot of nothing.
And yes, sure you can have shields. But again, what if shields cannot be used under certain circumstances, as I explained.
The WC4 missions were a good example of this - Pliers had to end up beefing up everyones armour.
Anyhow. BACK to WC...