In the film Donnie Brasco, there is a scene where Lefty (Al Pacino) comes to him with a diamond, without much hesitation Donnie (Johnny Depp) immediately identifies it as a fake. This later leads to the two of them paying a visit to a strip club owner who had originally given Lefty the diamond.
There are two possible scenarios that come to mind:
- Donnie actually knew the diamond was fake and was showing off his knowledge and connections to become a friend of Lefty.
- Donnie made the whole thing up as he knew the source would get a visit from Lefty and it would be an opportunity to become a friend of Lefty.
The first one, however, would imply that Donnie had extensive understanding of diamonds which would be nearly impossible to gain in the couple of years he is estimated to have been undercover so far at this point.
The second one, however, seems risky and careless. It would be easy for Lefty to get a second opinion which would put Donnie in a very bad position. Also if Donnie faked his knowledge on purpose in order for Lefty to pay a visit to the strip club owner it would mean that Donnie was aware that he was going to get him hurt. This doesn't seem like common undercover practice.
Did Donnie really know the diamond was fake?