Opals form from layer upon layer of microscopic silica spheres, the countless reflections brought on from eons of accretion giving impressions of nigh-infinite depth. Because there isn't a single crystal structure, they are more fragile than other gemstones, and can crack due to sudden changes in pressure or temperature.
Opaline Arcana is formed from layer upon layer of mental instabilities, the countless delusions brought on by eons of isolation giving impressions of nigh-infinite evil. And she already cracked a long time ago.
Now that Misty feels comfortable enough to discuss the topic, her new friends will find out just how deep the damage goes.
An ineligible entry for Imposing Sovereigns IV, using the prompt Opaline/Loyalty, set around Chapter 5 of Make Your Mark.