Alright, from what the guide tells me there are 112 diamond Cases in the North...I have 111 and cant seem to find the 112th. I have triple-checked every region so I doubt I missed one.
My only guess is in the top right of the map in Oasis, that mission where you go down some ladders, I'm pretty sure a case is there. Does that count towards the 221 overall? I'm almost positive I picked it up but that's the only thing I can think of stopping me from getting 112
AGH. Somehow even after looking over the map a hundred times I missed the diamond out in the desert(north east region)