emeralds are a type of beryl, on homeworld, beryls are typically soldiers who specialize in long-range attacks. they will typically be snipers while on-foot, but in ships they control they weaponry. emerald, being an extremely rare and valuable beryl, is the coordinator and commander of her own brigade of beryls. there are other emeralds who also have similar positions and their own beryls underneath them. emerald is "the perfect beryl", similarly to how jasper is "the perfect quartz".