Hm, I dunno what Moldsvite would be in the hierarchy. 

I'm going to go and say shes one of those think tank scientists. They are mostly used for their obtuse and outlandish thinking to come up with radical new ideas or technology. This gives them an air of unpredictability, which manifests in their powers tending to be different depending on that gem's personality or area of study or something of that nature. 

Due to this random nature, they aren't given any kind of leadership position or overseer position, and tend to be monitored more than anything. After all, you don't want a mad scientist caste to go out of control.