Nano technology is going to take us down this diamond road pretty soon if it works out. Deposited nano carbon particles are only a shade less perfect than a true diamond crystal, they'll probably hold up existing CMOS tech as the manufacturing techniques are refined. Using nano deposited carbon layers for gate and package insulation increases heat distribution and dramatically decreases gate capacitance. With ever and ever higher clock rates these insulation boundaries are the driving force in semi conductor manufacturing.
Nice to know we can just about obsolete the natural diamond from a material generation standpoint with technology. My wife would appreciate it as she abhors precious gems from a monetary and sentimental standpoint. She'd appreciate a random rock I picked up from the side of our street more if I'd put some thought into it and shaped it a little rather than some piece of cold rock that's been in the earth for a billion years and 6 months of my paycheck to acquire it. It's just pencil lead in a different form after all.
Reminds me, I need to find a random rock and put some effort into it.