Yellow Sapphire's Links
Yellow Sapphire was Matte Gold Pearl's owner for a time, and the source of a lot of MGP's mental problems. Though they have develop a vital connection out of necessity as their story progresses, the possibility of them ever having a healthy relationship is doubtful at best.
Matte Gold Pearl was assigned to Yellow Sapphire to be a "minder" so to speak, and run errands or do whatever the sapphire wished. YS didn't bother herself with the pearl's mental and emotional needs and so MGP became very depressed.