I know this isn't in the suggestions section, but I'd like to propose it as a "Secret recipe" to convert Industrial Diamonds into Vanilla Diamonds (And discussion thereof).
Let's face it, most people using IC2 are using buildcraft/Redpower in tandem, each using diamonds for higher end tech. What I am suggesting is a way to "burn" the impurities of the Industrial diamond, making it into a flawless (vanilla) diamond.
I personally think the best way of doing this is using the NukeGen, raising the Heat level to a Certain amount (At least 7k Heat), and giving it a small percent per cycle to convert each Ind. Diamond into a Natural one. I'm thinking of this as a parallel tech to the UUM, since a few people will be using their reactors to fuel Mass Fabs to make UUM for Diamonds anyway (9M Eu Vs 64 coal etc). This small chance and the amount of work needed to maintain a NukeGen at this heat should be a fair compromise one would think.