So, I've been seeing several designs for machines that produce diamonds from Coal, but most were pretty unwieldy, really expensive in terms of energy and sometimes hard to service if anything went wrong. Playing around in creative mode, I finally managed to put the whole machine (excluding in/output piping) in a 5 wide, 2 high and 2 deep format that allows access to every single machine and pipe and needs nothing but Coal Dust (or Coal if you add another Pulverizer) and energy in the form of MJ and EU to make diamonds. As with all the designs, it will take a stack of Coal (Dust) to make one diamond. For each diamond, it will require 7200 EU (9 operations of the Compressor) and between 48160 (with Coal Dust) and 73760 (if you need to pulverize the Coal first) MJ. As a byproduct, you will get an average of 80 Sand per Diamond.