Both burn, and can be vaporized with LOX/acetyline torches:
http://www.popsci.com/sites/popsci.com/files/styles/medium_1...
But apparently, over long periods of time, and unless coerced, carbon prefers to be graphite and so, diamonds can decay as such. [0]
[0] https://en.wikipedia.org/wiki/Material_properties_of_diamond...
Hence why graphite is generally more plentiful than diamonds.
And you're talking about burning, not storage. Coal produces lots of dust and debris. I'm sure diamond would produce some dust at volumes.
https://www.quora.com/What-is-the-difference-between-coal-an...
Anyway, it's fantasy because I'm fairly confident we're not going to turn CO2 into mountains of diamonds in my lifetime!
And you're talking about burning, not storage. Coal produces lots of dust and debris. I'm sure diamond would produce some dust at volumes.
https://www.quora.com/What-is-the-difference-between-coal-an...
Anyway, it's fantasy because I'm fairly confident we're not going to turn CO2 into mountains of diamonds in my lifetime!