While watching the movie in the theater for the first time, I thought this locket was pretty cool and thought i'd like to try my hand at making one, but 3 minutes of thinking about it I realized there had to be two versions as it just won't work to be able to twist it into a heart and then slide it open to reveal a photo. They had to have used 2 separate props. Then watching it again on my big screen I noticed that they indeed are 2 different props. The diagram is cool though and looks like you did a bang up job.
Nice.