I think SHE may be the diamond. She was in a relationship, and he was not careful, and he hurt her. She realizes that if he doesn't appriciate her, he's not worth it.
Also, it could be somthing other than her. Maybe he had a good life, or job, or was in a good relationship, and he was careless and just wasted it away. He "fell" while "holding diamonds."
I think SHE may be the diamond. She was in a relationship, and he was not careful, and he hurt her. She realizes that if he doesn't appriciate her, he's not worth it.
Also, it could be somthing other than her. Maybe he had a good life, or job, or was in a good relationship, and he was careless and just wasted it away. He "fell" while "holding diamonds."