Au where the Fe cast are all gems and Ariel is their diamond.

Other Gems

Anthony, Clive, Mathilda: Pearls, though Anthony is Ariel's right hand gem

Seliph, Matthew: Lesser Diamonds, Ariel treats all of them like equals

Jaffar, Nino: The adorkable Peridot duo

Leon: That one Garnet

Fernand: Just a raging Ruby

FE 7 Lloyd: An overprotective Opal

Saber: The most unlikely Sapphire