The Wired article which talks about folks being able to make synthetic diamonds very cheaply reminded my of a book by David Drake, in which futuristic mercinaries are armed with diamond bullets. Could one make a diamond bullet that wouldn’t shatter either from the explosion which pushed it out of the gun, or when it impacted on something other than flesh? Would the bullet be able to penetrate bullet resistant glass?
Why would you want a diamond bullet? What you want out of a bullet is high kinetic energy relative to its aerodynamic drag. This recommends extremely dense materials, hence the usual use of lead, and the use of the even more dense depleted uranium by the American military. Diamonds are extremely hard, but they’re not very dense at all, so I can’t see what advantage they would have.
Also their hardness works against them. Since the lands in the gun barrel can’t bite into the bullet they way the can with lead or steel-jacketed slugs, it would either seize, causing a breech explosion (really bad for the shooter), or would shatter, I suspect.
I think that says it all, Tuckerfan, but if the diamond were processed to be fired out of the gun, which has rifling, wouldn’t this wear down the barrel, unless it was diamond constructed, OMG, Overload. I think the article you cited best illustrates that the diamond is best for your wife or as a semi-conductor, if the get that pesky +/- thing worked out…
As I recall, the barrels were diamond or some other synthetic gemstone material, and the bullets were more like needles than your standard bullet. The reason they used them in the book, IIRC was because it penetrated the armor in use better than anything else available to them.
Hmmm, diamond bullets…
Sounds like a combination of two of the dumber James Bond movies.
Anyhoo, the shattering problem is the major stumbling block. Diamond’s hardness doesn’t translate to tensile strength. You’d be better off coating the bullets with a heavy metal, such as mercury (as is sometimes already done) or uranium (as is sometimes done on heavier artillery) or even teflon.
Besides, the main advantage to lead bullets is that they do flatten or shatter on impact, increasing their capacity to wound a human being. If you really want piercing power, chuck the handgun and get a good 5.56mm (or 7.62 when you absolutely positively have to waste every motherfucker in the goddamned room) rifle.
Umm…yeah. Well, ceramic bullets do exist, and have been tested by the military without seizing or shattering because of the rifling. One of my favourite ex-professors (the one who worked on the early M16) personally tested a ceramic 0.50 caliber round. They decided to drop it because it simply did not have the penetrating power of even a standard FMJ copper round, although it did not shatter or seize in the barrel.
A bullet could be made of diamond (which isn’t the same as ceramic, but shares similar properties), but the low kinetic energy would reduce its effectiveness in many ways. Also, bullet-resistant or bullet-proof glass is often of the multi-layered type which uses up the kinetic energy of the bullet in shattering different layers of the glass, while the multi-layered design prevents crack propagation through the entire medium. Look closely at bulletproof glass and you’ll see that it’s often of this style. So it’s debatable whether or not diamond would be the same or less effective versus bulletproof glass - my WAG is that it would be less effective.
Cite? The only respectable reference to cermaic bullets I could find is thus:
IIRC, the tungsten KTW bullets use a copper cup to engage the rifling. The same principle could be used for a diamond bullet.
The biggets problem would be that the lighter weight of the diamond bullet means that it’s shedding velocity a lot faster than a lead bullet, which isn’t very desirable. You’d be better off with one of the other standard AP bullets out there.
–Patch
I’m surprised at all you naysayers and tut tutters.
The question is: can you make a bullet out of a diamond.
The answer would be: yes, but likely a pretty crappy one.
But c’mon, a diamond bullet isn’t about efficiency and kinetic killing power. A diamond bullet is a signature. A diamond bullet is a style.
I bet it’ll be a long time before you can afford to fill a banana clip with them.
And you’ll be able to buy your ammunition at Tiffany’s. 
–Patch
Didja read the Wired article? They’re talking about retailing synthetic (or “cultured” diamonds) for $5 a carat. Depending upon how many rounds the banana clip holds, I might be able to afford 'em.
The obvious solution is to put the lands on the diamond bullet and let the bullet rifle the barrel!
OLD CHINESE PROVERB
What one fool can do,
Another can!
…well, I suppose they’d be usefull if you needed to kill Emma Frost. 
Anyone feel like discussing the ballistic properties of an adamantium bullet?
I hear sapphire bullets are made of pure love.
/Five points for getting that reference.
TMBG.
Can I cash in those points now?
To shoot at the Gorn, of course.
So, would osmium be an even better bullet material than depleted uranium? (Assuming money were no object.) Or would it be too brittle?
I sent an e-mail to them inquiring about a purchase. They replied in the range of $1500 a carat.
Theoretically, if everyone had one of these CVD machines in their backyard, the production cost would be 5 bucks a carat. Thats a long ways off, unfortunately.
I told you my cite, it was an anecdote that doesn’t happen to show up in a Google search. They were made of the same Si3N4 that ball tube mill balls are made of, which are quite tough.
I’m sorry you feel that my reference is not “respectable” because you cannot Google Search for it, but then I’m not trying to answer questions I shouldn’t be answering or which are outside of my professional knowledge base in GQ just to pad my post count, so Google is not my crutch.
Can you give me a cite for the “Since the lands in the gun barrel can’t bite into the bullet they way the can with lead or steel-jacketed slugs, it would either seize, causing a breech explosion (really bad for the shooter), or would shatter”? Your cite (the “respectable” one) you found did not mention the lands needing to bite into the bullet, thus leading to explosions or shattering. So you must be relying on a non-Googlable source yourself - I guess you’re just as “respectable” as I am on this subject. Why is your non-linked source is better than mine?
FTR, having seen the results of seized bullets many times down at the gun repair shop, I can also say that a seized bulet does not mandate a “breech explosion”. Seized bullets are removed from guns from time to time. Yes, guns sometimes explode too, but typically this is due to an overpowered self-load combined with a defective barrel, receiver, or block.