The oldest gem, who mostly does patrol duty. They're partners with Zircon. Yellow Diamond is cheerful yet mature, and feels responsible for all of their siblings.
Throughout their life, Yellow has had several partners—Green Diamond, Ruby, Sapphire, and Pink Topaz—but they were all taken to the moon. Yellow struggles with low self-esteem and possible self-loathing for constantly letting their partners be taken by the Lunarians, and also questions why they bother fighting anymore.