20 March 2014

Diamonds are not forever

A thread at Reddit addressed the question "If diamonds are made of just carbon, is it possible to get a diamond to catch fire?"

The embedded video answers the question by showing a diamond being burned (heated white-hot, then dropped in liquid oxygen).

Practical significance, for those without liquid oxygen at home and diamonds to burn?
If your house burns down with the family jewels inside, you can collect the pools of melted gold, but the diamonds will be gone in a puff of CO2. Cheaper, more attractive stones, such as cubic zirconia and synthetic ruby and sapphire, are made of refractory metal oxides that easily withstand the same heat. So it's actually mall trinkets, not diamonds, that are forever.


  1. Our inherited diamond came with the story that my great Aunt had not noticed when the ring slipped off of her finger into the wood cookstove. Once the fire died down the diamond was retrieved and reset into a new gold band. This was nearly 100 years ago, I would guess before the days of synthetic jewels. Maybe the fire wasn't hot enough? Or maybe the story isn't true. Damn you! scientists for squashing all my beliefs.

    1. "Being a form of carbon, diamond oxidizes in air if heated over 700 °C. In absence of oxygen, e.g. in a flow of high-purity argon gas, diamond can be heated up to about 1700 °C".

      If her ring fell into a wood cookstove and got between the logs and into the ashes, it could perhaps have been in a low-oxygen environment where it didn't combust.


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