Diamond is a gray-and-white she-cat with misty green eyes.
She is a kittypet who lives in the same house as Lilian, Lily and Diamond's House. When Winter and Lizzy eat the kittypet's food, she seems not to care, and lets them continue eating. Unlike Lilian, she doesn't care much about kittypet things, nodding in a bored fashion when her friend tells the other kittypets what their Twoleg brought them. She shows interest in the Clans, and hints at joining a Clan one day.
Later, when Winter and Lizzy invite her to join them, she agrees, despite Lily's protests.
- "She barely spends time at the house anymore. She might as well be one of those forest savages!"
- —Lily on Diamond Lily and Diamond's House, on Feb. 2nd, 10