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  #1  
Old 05-25-2006, 06:34 PM
Rune Rune is offline
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At what temperature do diamonds ignite?

One James Bond movie (Diamonds are Forever, probably) featured a corpse with some diamonds on him being cremated, and Mr. Bond picking up the diamonds from the ashes. Now I have no idea if a cremation fire is hot enough to ignite coal, but since diamonds are made of the same material as coal structured a bit different, wouldn’t it be natural to assume diamonds ignite at the same temperature as coal (and it than case would have burned up in the creation fire, if it was hot enough to ignite coal)? So at what temperature do diamonds burn?
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  #2  
Old 05-25-2006, 06:40 PM
Tapioca Dextrin Tapioca Dextrin is offline
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800 deg C.

Typical crematorium temperatures are in the region of 900 deg C
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Old 05-25-2006, 07:13 PM
LiveOnAPlane LiveOnAPlane is offline
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I saw that movie a long, long time ago. But I also watched the rerun on TV maybe a year or so ago. But anyway, feel free to slap me down if I have erred.

Your question is a good one. I just think, from what I remember, that in the movie, Bond secreted the diamonds inside a corpse.

Paraphrased:
Leiter: "So where did you put the diamonds, James?"
Bond: "It's alimentary, my good man."

I do not recall that corpse being cremated. I do recall JB being pulled out of the crematorium in the nick of time because the Mafia-types discovered that the diamonds he delivered to them were in fact fake.

Got nuthin' beyond that.
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Old 05-25-2006, 07:38 PM
Chronos Chronos is online now
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Quote:
Now I have no idea if a cremation fire is hot enough to ignite coal, but since diamonds are made of the same material as coal structured a bit different, wouldn’t it be natural to assume diamonds ignite at the same temperature as coal (and it than case would have burned up in the creation fire, if it was hot enough to ignite coal)?
One could similarly ask, since diamonds are made up of the same material as coal structured a bit diffferent, shouldn't diamonds be as easy to cut or scratch as coal? The structure of diamonds is a very stable structure, which leads to them being more durable than coal in many ways. They don't scratch as easily, they don't melt as easily, and they don't burn as easily.
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Old 05-25-2006, 08:08 PM
kanicbird kanicbird is offline
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Quote:
Originally Posted by Chronos
The structure of diamonds is a very stable structure,
actually the structure is unstable, slowly converting to graphite, but it does take a very long time. IIRC heat accelerates this.
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Old 05-29-2006, 04:00 PM
WarmNPrickly WarmNPrickly is offline
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Yes diamonds burn. Faraday burned a diamond in pure oxygen. I can't find the temperature. Frankly, the gain in entropy from converting a solid (effectively a single molecule) into a gas (billions of molecules) suggests that diamonds should burn, but perhaps without pure oxygen they would first convert to graphite.
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Old 05-29-2006, 04:31 PM
Mangetout Mangetout is offline
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I don't think it's explicitly shown in the movie that the diamonds were retrieved from thwe ashes; I had assumed (perhaps wrongly) they had been removed from the corpse prior to cremation and placed in the urn afterwards - i.e. that they did not go though the furnace.
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Old 05-29-2006, 10:54 PM
WarmNPrickly WarmNPrickly is offline
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diamonds burn at approximately 800 degrees centigrade provided there is enough oxygen around.

http://en.wikipedia.org/wiki/Diamond...amic_stability

look at thermodynamic stability
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  #9  
Old 05-30-2006, 12:47 AM
David Simmons David Simmons is offline
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Quote:
Originally Posted by Rune
One James Bond movie (Diamonds are Forever, probably) featured a corpse with some diamonds on him being cremated, and Mr. Bond picking up the diamonds from the ashes. Now I have no idea if a cremation fire is hot enough to ignite coal, but since diamonds are made of the same material as coal structured a bit different, wouldn’t it be natural to assume diamonds ignite at the same temperature as coal (and it than case would have burned up in the creation fire, if it was hot enough to ignite coal)? So at what temperature do diamonds burn?
On the same line, the final scene in Treasure of The Sierra Madre shows gold dust being scattered by the wind. Gold dust doesn't blow away very easily and in fact pulverizing the ore and blowing air through the dust (winnowing) is a crude way to separate the gold from the dross.

You just have to suspend disbelief because the scene isn't about gold dust blowing away. It's about Humphrey Bogart, the most avaricious of the prospectors, being killed for his mules (as I recall) while the gold dust that he worked for so hard blows away like feathers.
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Old 05-30-2006, 10:10 AM
Duke of Rat Duke of Rat is offline
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I saw a show on diamonds, they heated one red hot and dropped it into a saucer with liquid oxygen in it. The diamond burned to nothing.

As for the gold dust in TotSM, I was under the impression that it was dust blowing away when Bogart was killed. He had hidden the gold and filled the bags with dirt. When he was killed, there was no way to know where he had stashed the gold. That's my take, anyway.
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  #11  
Old 05-30-2006, 10:26 AM
Duke of Rat Duke of Rat is offline
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I guess I had it wrong about the gold dust. It says Here that it was gold dust in the bags, the banditos thought it was just sand to make the hides weigh more. I thought it was just sand, too. I've never seen gold dust, and the movie was in black and white, I figured the banditos would know the difference between dirt and gold. Guess not.
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  #12  
Old 05-30-2006, 10:36 AM
Pleonast Pleonast is offline
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Quote:
Originally Posted by Duke of Rat
I saw a show on diamonds, they heated one red hot and dropped it into a saucer with liquid oxygen in it. The diamond burned to nothing.
Or, more precisely, burned to CO2. Remember kids, don't burn your diamonds--it contributes to Global Warming.
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