I imagine assessing rough diamonds for their “future potential” is a “hands on” learning process over a long period of time. A rough diamond has to first assessed according to its shape and the position of any flaws. Then the best shape to maximize weight / minimize flaws has to be established before cutting can begin. I’ve seen a few rough diamonds in person and they looked like they had a film on them similiar to weathered glass pieces you might find on the beach. And none I saw looked anything like I expected ie the classic pyramid on pyramid shape.
Are you trying to do this in the US or somewhere else? No, GIA doesn't offer anything in this area (other than identification, which is pretty easy).
Try these guys in Florida although where you go depends on where you want to end up. This is mostly a diamond cutting school (as far as I know, it's the only one in the US) http://www.diamondschool.com/