# Diamond Myths **URL:** \ **Category:** Factual Questions\ **Created:** [December 10, 2015, 11:43pm UTC](https://boards.straightdope.com/t/diamond-myths/740133 "2015-12-10T23:43:51Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Leonard33](https://avatars.discourse-cdn.com/v4/letter/l/e8c25b/32.png) [@Leonard33](https://boards.straightdope.com/u/Leonard33)\ **Post date:** [December 10, 2015, 11:43pm UTC](https://boards.straightdope.com/t/diamond-myths/740133/1 "2015-12-10T23:43:51Z")
Hello peoples of the message board. My friend Socrates (Ironic, really he’s as dumb as a rock). He claims that you can smash a diamond into a liquid. _Sigh_ I told him that you can burn a diamond. It is pure carbon. It is a glorified piece of clear charcoal. He disagrees. I would like to see whom is wrong. In this post, I would like to also debunk other myths about diamonds. The more, the merrier. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [December 10, 2015, 11:50pm UTC](https://boards.straightdope.com/t/diamond-myths/740133/2 "2015-12-10T23:50:31Z")
It seems that liquid diamond is kind of possible… > [@](#): > > scientists from Sandia National Laboratories, successfully melted diamond years ago, but they were unable to measure the pressure and temperature at which the diamond melted. > [@](#): > > When diamond is heated to extreme temperatures it physically changes, from diamond to graphite. > > The graphite, and not the diamond, then melts into a liquid. The trick for the scientists was to heat the diamond up while simultaneously stopping it from transforming into graphite. ---
**Author:** ![Leonard33](https://avatars.discourse-cdn.com/v4/letter/l/e8c25b/32.png) [@Leonard33](https://boards.straightdope.com/u/Leonard33)\ **Post date:** [December 10, 2015, 11:53pm UTC](https://boards.straightdope.com/t/diamond-myths/740133/3 "2015-12-10T23:53:54Z")
> [@bob\_2](#): > > It seems that liquid diamond is kind of possible… Really? Would it first melt or burn? ---
**Author:** ![snowthx](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/snowthx/32/10660_2.png) [@snowthx](https://boards.straightdope.com/u/snowthx)\ **Post date:** [December 11, 2015, 12:01am UTC](https://boards.straightdope.com/t/diamond-myths/740133/4 "2015-12-11T00:01:44Z")
The master speakith, regarding if [a diamond’s price is a true measure of it’s value](http://www.straightdope.com/columns/read/2524/is-a-diamonds-price-a-true-measure-of-its-value). In a word - no. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [December 11, 2015, 12:07am UTC](https://boards.straightdope.com/t/diamond-myths/740133/5 "2015-12-11T00:07:25Z")
> [@Leonard33](#): > > Really? Would it first melt or burn? Burning requires oxygen (or an oxidizer). Presumably there must be some sort of atmosphere in which you could liquify it without burning. ---
**Author:** ![the\_diego](https://avatars.discourse-cdn.com/v4/letter/t/7bcc69/32.png) [@the\_diego](https://boards.straightdope.com/u/the_diego)\ **Post date:** [December 11, 2015, 12:12am UTC](https://boards.straightdope.com/t/diamond-myths/740133/6 "2015-12-11T00:12:05Z")
A geology multiple choice question: “This mineral has no streak. At high temperature it oxidizes cleanly, leaving no ash.” ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [December 11, 2015, 8:27am UTC](https://boards.straightdope.com/t/diamond-myths/740133/7 "2015-12-11T08:27:37Z")
> [@Smeghead](#): > > Burning requires oxygen (or an oxidizer). Presumably there must be some sort of atmosphere in which you could liquify it without burning. Nitrogen would be the most common “inert atmosphere”, there’s others (noble gases, such as argon) but they’re more expensive without necessarily being better for your use. Which one you chose would depend on what impurities were acceptable at what levels (the most problematic ones tend to be oxygen and water, having a bit of nitrogen in your argon wouldn’t generally be considered a problem). ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [December 11, 2015, 1:10pm UTC](https://boards.straightdope.com/t/diamond-myths/740133/8 "2015-12-11T13:10:33Z")
[Here is a phase diagram for carbon.](http://dao.mit.edu/8.231/CarbonPhaseDia.htm) Phase diagrams are a common tool in thermodynamics and chemistry, and are useful for understanding how a substance behaves under different combinations of temperature and pressure. In that diagram, the vertical axis is measured in kilobars; 14.7 psi = 1 bar = 0.001 kilobar, so the chart runs the range from 147 psi at the bottom all the way to 14.7 _million_ psi at the top. Most of the phase diagram is taken up by the graphite phase; if you’ve got a pile of carbon at low-to-moderate temperature and pressure, it would like to be graphite. The diamond in your wedding ring was formed at hideously high temperatures and pressures, but now that it’s on your finger it would like to become graphite - but it’s in a kind of “frozen equilibrium,” only able to change to graphite _very_ slowly; it’s going to take a long time. If you heat it up (without oxidizing it), it will turn to graphite more quickly. If you heat it up even more, it will turn to vapor (after briefly existing as graphite). At higher temperatures/pressures, phase changes will take place more quickly. The phase diagram shows graphically what **bob++** quoted: > [@bob++](#): > > > [@](#): > > > > When diamond is heated to extreme temperatures it physically changes, from diamond to graphite. > > > > The graphite, and not the diamond, then melts into a liquid. The trick for the scientists was to heat the diamond up while simultaneously stopping it from transforming into graphite. The phase diagram shows that you have to apply a pressure in excess of 100,000 atmospheres (1.47 million psi), AND you also have to heat your diamond up past 4200K (7100F). If you don’t have both of those, your diamond will become something else before it becomes liquid. Note also that using the term “liquid diamond” is equivalent to saying “liquid ice;” i.e. it’s a bit nonsensical. “Liquid diamond” isn’t diamond anymore - it’s liquid carbon. Diamond is by definition a solid phase of carbon (so is graphite), just as ice is a solid form of water.