vault and loot the diamonds, then exit to find plenty of enemies to stop you from getting away. one of those enemies will be a heavy, which will probably be the first one you see as soon as you exit. kill them all and bring the diamonds to the drop-off point to finish the mission. it's time to use the bomb, and when it is truly in your power to use the bomb, the final guns could be not just the final guns, but the honest-to-god beginning of the no-kidding final guns--and that is very frightening. 