the movie starts with a girl and a boy that start dating and fall in love and we think that both are lower-class. eventually we figure out that the girl is rich when the friend of the guy is working in a club and sees the girl. They are both black. in one scene the guy gives her a necklace and after he learns that she lied he takes the necklace away from her.
This is from the movie ATL
http://www.imdb.com/title/tt0466856/