So short, still-workin-on-it version: these two little babies (not actually little) have a bit of a garnet situation going on, being (or wanting to be) pretty much fused all the time.
Which of course was not regarded well by homeworld, etc etc got in trouble etc when it was heard they were wanting to join the Rebels there was a big HELL NO and larimar was sent to put em out.
Which she did and they’ve been stuck in larimar’s damn trophy box ever since. Mostly because larimar knows they’d kill her on the spot if she let em out.

Cymophane is a pretty typical gem, not sure what she used to do yet.
But she is responsible for making sure Agate didn’t get culled Immediately

AGATE….. Is very..defective. She’s from a kindergarten (not earth) and her gem just formed all wrong, into this weird geode-y thing. This affects her projection pretty severely, and she just Can’t form 100% of it. She’s reformed a few times though, and worked out a more functioning body since her first (when she first popped out of her hole..think just having big chunks scooped out of her). THIS IS THE BEST SHE CAN DO..

They do have clothes I just…haven’t thought of them yet. Agate has a poncho though.