The correct answer to this open question is the following.
You forgot to include the name of the film. Without the name, we do not have the correct reference.
So we have to do further research to comment on the following.
If you are referring to the issue of the diamonds and the atrocities committed in Sierra Leona, Africa, the people that appear in the film is local people from Sierra Leone that is controlled by other powerful groups, greedy groups that have no moral to commit the kind of cruel activities in order to get the diamonds and make profits.
These groups and people traffic with diamonds that are sold to other people. To get the diamonds, many poor people in Africa are exploited, paying them low salaries to get the diamonds.
The business of diamonds is a multimillion activity that is handled by some mafias. Cruel mafias that do not touch the heart to kill in order to exploit and control this business. People who buy these diamonds are not aware of the violent behavior and exploitation of people to extract the diamonds. There is an illegal market of diamonds that only make things worse.
This greed behavior is so questionable and governments should attend this problem that causes too much violence and deaths.