Campaign: Diamond Distribution ?

[Seamndel]

I understand there are supposed to be 1000 diamonds in total, 380 of which in the Northern map; 112 briefcases. 

I currently have 377 diamonds; 112 briefcases. I still haven't traveled fully into the Southern map but I did take 2 briefcases in the middle map ("Central desert").

 

Since the numbers don't add up, would I be correct in assuming I actually have found only 110 cases in the North; have ~375 northern diamond and am missing 2 other northern cases which would add up to 380?

 

There are no good guides on the web regarding the exact distribution of diamonds between the districts , with clear division of the desert middle map.