I believe that matters of interpretation are personal, subjective and best be kept out of communications, but you so nicely, than I'll share my piece of it: The story, shortly, is about a rich girl that falls in love with a poor boy that persuades her not to commit suicide, her family and friends won't like the idea, so she keeps their relationship secret, the necklace than, symbolizes her background, social, economical, behavioural and so on, the necklace is made of gold as I remember, and it is around her neck, ball and chain kind of thing, getting rid of the necklace means leaving home and turning to super awesome life of poor but rich with mystery mr. DiCaprio.
