Phosphophyllite

Phosphophyllite (フォスフォフィライト, Fosufofiraito), or Phos for short, is the main protagonist and the youngest Gem when the story began. They're weak, brittle - not suited for battle - and their clumsiness makes them difficult to maintain any other roles. Phos has always wanted to be useful.

Phos's initial job was to make a natural history encyclopedia which they progressed very little on. They promised to help Cinnabar find a job suited for them as well.

Phos so far is the only Gem who has had drastic body and personality changes.

• Their hardness is three and a half. The youngest, at three hundred years old amongst the jewels. They are brittle and weak, so they are not suited for battle. They are clumsy and ineffective and cannot do anything, but they are given the job of completing an Encyclopedia -- The first job they've had since they were born.[8]