What temperature/pressure/amount of carbon for Superman to make a nice engagement ring diamond?

[Leo Bloom]

See subject. I've always seen him start with a briquette, which my gut tells me is not enough source material.

Other chemical transformations are allowed, if they require less energy, for lesser credit.

I've wondered about this for a long time. Honestly.

[MikeS]

If you believe the numbers I found by Googling, charcoal has a density of roughly 0.4 g/cm³, while diamond is somewhere around 3.5 g/cm³. If that's accurate, and the charcoal is mostly carbon, then the resulting diamond will have about one-ninth the volume of the briquette. To put it another way, if the briquette has a mass of 20 grams, so will the diamond. (Remember that one gram = five carats.)

I'd be more concerned about impurities in the diamond arising from the "ash" (i.e., non-carbon) in the briquette; the resulting diamond might not end up being gem-quality. You'd probably want purer carbon to do it properly.

[Mahaloth]

Based on how strong the comics currently have him at, is Superman strong enough to do this? Is Hulk if he is maxed angry? I have to think they aren't, right?

[Exapno Mapcase]

Originally Posted by MikeS

I'd be more concerned about impurities in the diamond arising from the "ash" (i.e., non-carbon) in the briquette; the resulting diamond might not end up being gem-quality. You'd probably want purer carbon to do it properly.

Not gem quality?! Every time he does this, it appears in his hand completely cut, faceted, and sparkling!!!

[Michael63129]

Here is an idea of the pressures and temperatures involved in making artificial diamonds:

Man Made Diamonds

The machine reaches 1,500 degrees, and the pressure on the core is 850,000 pounds per square inch -- that's equivalent to 100 8,000-pound elephants standing on a coin. Once the machine is closed, nature takes over. Four days later a very crushed core is taken out, and a man-made diamond is inside.

Not only would he have to apply 850,000 PSI and 1,500 degree heat (no units, but even Fahrenheit is hot), he would have to do it for four days. Plus, a seed diamond is needed to start the crystallization process. The reaction might occur faster at higher temperatures and/or pressures, and possibly need no seed, but this is already highly unlikely even for a superhero (sure, even an ordinary person could apply 850,000 PSI if the points were small enough; applied over an area 1/100th x 1/100th of an inch, that would need only 85 pounds of force, but that is one small diamond).

[TriPolar]

The strength limits for Superman and the Hulk are bound by imagination, not physics, so either could do this easily. The Hulk would simply have to get mad enough at a lump of coal, and he could crush it into diamond in seconds by far exceeding the pressures that can be produced by man-made machines. Superman would additionally be able to heat up his hand with his heat vision, requiring less pressure. The Flash could probably make a diamond by shaking a piece of coal really fast, something no natural process may be able to do. And while Batman could easily build a machine that turns coal into diamonds, he doesn't have to because he's freakin' rich and can just buy diamonds.

[Una Persson]

Originally Posted by MikeS

If you believe the numbers I found by Googling,

Or you could try this website called "The Straight Dope" which is written by this guy named "Cecil Adams." I don't know; it's obviously quote obscure.

[Alan Smithee]

Well, I guess Cecil's a Marvel guy, huh, Una? I think it's well established that Superman can generate and withstand limitless force and temperature, so I don't have a problem with those aspects. He also has excellent muscle control that - at least in the Golden Age - allows him to alter the contours of his face in order to disguise himself. Still, he's not a shapeshifter, so there must be some limit to his ability to contort his body. I agree with Cecil that the geometry of compression is the tricky part, but I think Superman can probably do it.

OTOH, how can he use his heat vision on the coal while he's squeezing it? Can he focus his heat vision through something? If he heats up the outside of his hands, he'd vaporize everyone in Metropolis, and I'm not even sure his body would conduct the heat to the coal!