[Cvengr]

Since Diamond defines a crystallographic structure, this a bit misleading. Especially, when the diamond gemstones we associate with the colloquial term "diamond" is made up of pure Carbon in its pure form.

There may be other compounds which the crystals are arranged in the diamond matrix, which might also be called diamond, provided they assume this matrix.

There might be impurities or polycrystalline interlockings which attribute to a possible higher hardness, but generally the strength is decreased.

[decimon]

I’m too lazy to research this but...isn’t natural diamond carbon 12? Hasn’t a carbon 13 been synthesized?