Diamonds are very expensive and the ladies are attracted to them. This much I know from first hand experience. Most men, as far as I can tell, have only a passing interest in the gemstone and a faint realization that they’re going to have to buy one (or at least a very convincing replica of one) at some point in the future for their significant other. But, from a physical standpoint, (as chemists, mind you) it’s hard not to be enamored by the crystal structure of diamond and the appreciation that its robustness is tempered by its thermodynamic instability – eventually that precious rock will be graphite – a fact jewelers are often not willing to consider when negotiating prices. There’s also the refractivity of the material that gives it a very appealing luster when cut properly. These cuts, some of which are in the public domain (like the “Princess cut”) and others which are very much not, create the responsible luster in an otherwise prosaic, transparent rock.
It was with interest then that I came across Toshikazu Sunada’s article in Notices (link) (I think it’s the Mathematical equivalent of C&E News) where he proposes, rather oddly, to create a crystal of equal brilliance by replicating two properties of diamonds – namely “very big symmetry” (?) and a “strong isotropic property” (not “isotropic” in the sense a crystallographer may use it.) So… he proposes a chiral structure. Naturally, when you’re going for maximum symmetry you instinctively reach for chirality. (??)


Hmmm… I pulled those from the paper and added a few words to make it clear. I certainly hope it helped. Careful inspection of the right image (don’t get a headache) shows some seriously fucked up rings in there. To better illustrate them, I’ve pasted them below:

Which produces a chiral crystal. Can this be made, Sunadad wonders to himself…. aloud… and in print… using JUST CARBON. He certainly seems to think this is possible. I’m… err… not so sure. The paper has his proposed chemical structure (with double bond) but I’m thinking it’s not going to happen. He’s a mathematician, so his fanciful structures are easily forgiven – and even then, I’m not going to say it’s impossible. But… I’m not going to say it’s possible either. So, for you materials chemists that get their jollies making crystals with fucked up properties, here’s something to go for. You’ll at least make a few mathematicians happy.
Thanks to Eximer, I discovered that Slashdot has comments and found one that’s actually useful to this discussion. I was happier before I realized Slashdot had comments.



Meh. I’ll leave this one to Uncle Al in his kitchen.
Clear diamonds are pretty and rather boring. But if you dope them with boron they become dark blue and semiconducting.
Did anyone read the comments thread for this on Slashdot? It took two comments until people started talking about the De Beers cartel. Two. And about a hundred before someone finally mentioned “hey this can’t be made.” God I hate Slashdot.
Slashdot is great if you have a lot of free time and no desire to get useful information (well, if you have the time to sort the useful information from the nonuseful information). It’s funny sometimes, but has a tendency towards groupthink and anti-groupthink modes, and has a lot of people who don’t know much about any given topic. I used to read it too much.
I can’t wait for Grandma to kick the bucket so I can turn her into diamonds.
http://www.lifegem.com/
I’m not sure if her diamonds will be chiral or not. Worth a try.
That’s fucked up.
yea, I heard about this too. In loving memory of your mother in law. The resulting ugly little yellowish diamnond must be a perfect gift for your wife.
How could you keep yourself from barfing every time you looked down at your ring and thought that it was made from your mother? It’s just fucked up, man.
It almost sounds like something a serial killer would do (I think that giving items obtained from killings of people symbolic of a desired target to the actual target is a standard behavior).
It seems a little tacky, though if you’re a recent lottery winner, you could put your mother-in-law in a nice setting and include her in a velvet picture of Elvis or as a star in a Thomas Kinkade print or something like that.
i hate slashdot so so much
Silly mathematicians.
Mitch
Hey, some of us do wind up doing useful shit, like character tables.
Kyle, your statement makes it sound like you were happier before you met me. This is undeniably true, but you are rude to state it so baldly. I’m going to go cry about it and write a song about it.
huh?
He even spelled my pseudonym wrong. Sigh. With friends like these…
He didn’t even plug your site either.
Yeah, what a dick.
Kyle is basically the Maddox of the chemical blog universe
Well then… where’s by fuckin’ book deal?
There are 13 chiral cubic crystallographic space groups (#195-199, #207-214 inclusive). Still… feh. If you like glitter and dispersion get a properly cut stabilized cubic zirconia. You want yttria not lime stabilizer. You want a fully oxidized gem – skull melting and crystallization output is oxygen-deficient for electrical conductivity for induction heating. It’s yellowish.
Roald Hoffmann suggested a lovey carbon allotrope. Start with a plane of parallel, aligned, suitably spaced, all-E-polyacetylenes (trans back in the good old days). Next layer down is that plane parallel to the first and rotated 90 degrees. All the interior loose bonds line up. Stack ‘em alternately and surface terminate with hydrogen caps. Synthesis is left as an exercise for the interested reader.
Dont sweat bulk diamond reverting to graphite under ambient conditions. The activation energy is about 90% of the total lattice energy. Stable to about 1000 C in air and about 1500 C in inert or reducing atmospheres. OTOH, if there is a nucleation site, yer screwed. Look at the density difference. Once the transformation starts it goes like corn popping.
White diamond is the worst blackbody radiator. Diamond at 900 C does not visibly glow. Check out its Debye temp.
Lattice volume of Hoffmann’s all-E-polyacetylene carbon allotrope in HyperChem *.hin format,
http://www.mazepath.com/uncleal/hoff2.hin
As Uncle Al said, thermodynamically unstable but kinetically stable, for human purposes at least.
For anyone interested in a diamond-like stone without the cartel/politics issues, a pretty neat alternative is synthetic Moissanite, SiC.
http://en.wikipedia.org/wiki/Moissanite
Moissanite is birefringent not optically isotropic. Look through the side of the gem – doubled glitters with shared intensity. Polariod sunglasses and look through the side as you rotate the gem around the viewing axis. Bulk Moissanite is perceptibly greyish and unsuited to more than ~carat sizes.
Your average natural diamond is about a billion years old. That’s slower reaction than dissolving CoCl3(anh) in aerated distilled water. That a diamond is a covalently-bonded single molecule is ever so trippy.
It’s like, every sentence should be its own paragraph or something.
and each carved onto a tombstone
in lieu of a meaningful comment: SiC is shiny!
Yeah, but that ad doesn’t say diamonds are for like 50,000,000 years. It says forever. Lawsuit. Try to convince your fiance to get a phial of graphite instead of a diamond on the grounds that it may, in fact, last forever. Hell, if carbon allotropes are her thing, even a one carat buckminsterfullerene would provide her with spheres of happiness–and save a bundle on the transaction too.
I once saw a documentary about synthetic diamond production – they talked about Gemesis and Apollo Diamonds – but to me the most impressive sight was General Electric bulk production of technical diamonds. They were yellowish, uncut and rater large stones – up to quarter-inch size, nontransparent but with geometric shapes and great luster. And they had 2-liter-sized jars all over the place, filled with this stuff! And the large warehouse-like hall somewhere in Kansas, full of these giant presses. They crank out a new diamond every 15 minutes on these machinces, it has a coroussel autosampler so that the hot finished cubes cool while other are loaded and pressed.
And then of coure microdiamonds made by underwater explosions of TNT, in kilo-sized charges. Too bad the purified explosion-produced product does not look very exciting.
I think it would be very sexy to lease out a Gemesis diamond press and use a one-of-a-kind mixture (specify nitrogen, boron content for color of choice) and give it as a ring, chuck out the rest of the batch… That way, you actually made it yourself and there’s a personal touch.
Kinda like this:
http://xkcd.com/260/
A practical consequence of old arguments: http://www.thecrimson.com/article.aspx?ref=521522
Can we get universities to offer dating grants for dating-underrepresented minorities, so that anyone who joins into a monogamous relationship with a dating-underrepresented minority gets a stipend (bonus for interracial couples)? This will hasten the eventual coalescence of races into one gemisch and thereby end the race question once and for all.
Perhaps the Campus Republicans would like to sponsor this. (Didn’t the yale campus Republicans wind up with a Hispanic club president award a “whites-only scholarship” to a half-black student?) Maybe I’m making the “yale” and “half-black” part up.
Hey, I saw something similar to your 10 membered ring picture in this recent paper on the third page.
http://pubs.acs.org/cgi-bin/ar.....75408b.pdf
That’s about the same time I stopped reading this article since it’s beyond me. I’m not big on crystal stuff. Still, it was a pretty interesting idea and the crystal is a ‘flexible’ network. I bet it’s a conductor as well and not an insulator since it’s aromatic and metally.