[deconstructionist]

This question is admittedly so stupid I'm almost ashamed to ask... But here goes. Flame me if you must.

Fossil fuels are carbon-based energy. Oil and coal are formed from organic matter being compressed and heated for millenia. Diamonds are what comes next after coal, right? If you continue to compress and heat coal for more millenia you get diamonds, more or less?

Is there energy contained in diamonds and/or other gemstones? If so, is there any way to release this energy?

obviously it's not economical i'm just curious...

[Kingcoal]

Diamonds are carbon and do oxidize, but the energy released is about the same as the equivalent amount of anthracite. Are you Polish?

[ChumpusRex]

You can burn diamonds but they don't burn very easily.

You need to get them white hot in an atmosphere of pure oxygen before they will burn satisfactorily.

Most other gemstones are already oxidised (oxides, carbonates or silicates), and so won't burn.

[Windmills]

All the energy applied to create a diamond isn't stored in the diamond. Once the energy required to change the carbon microstructure from on form to another has been expended, the rest just increases the temperature. All of that heat leaks away in one way or another as mined diamonds come to thermodynamic equilibrium at the surface of the earth.

Also, heating and applying pressure to carbon materials won't give you a diamond, no matter how many thousands of years you do it. You're more likely to get graphite. You need sustained very high temperatures and pressures to generate diamonds.