Cinnabar

Cinnabar is the only Gem who goes on night patrol. Due to their body producing a poison (Mercury) which is harmful to Gems and living things, they are isolated and ashamed of themselves. They hate fighting and hate to be seen. According to Rutile, Cinnabar has an extraordinary amount of talent and combat ability, but is too much to handle due to their uncontrollable poison that ruins everything it touches. Cinnabar's silver poison gathers faint light at night, which keeps them awake and aware while night patrolling. According to Kongo-sensei, the night patrol is something Cinnabar came up with...