Yellow Diamond, or Yellow for short, is a Homeworld Gem and a member of the Great Diamond Authority that formerly ruled over the Gem race. In particular, she commanded her now-disbanded military and oversaw Gem production on her colonies. She was first shown in the extended theme song before making her official debut in "Message Received".

As a result of Era 3, Yellow now works to repair Gems she had previously shattered in her Cluster experiments and wishes to use her powers to help other Gems alter their physical form if they choose to do so.