The Color of Magic? GNU Terry Pratchett


The color most likely has to do with what element the energy source aligns with. Ceruleum being blue could mean it's water/ice aligned, though it is flammable and volotile. That being said, in the Eighth Umbral Calamity, Black Rose rendered Ceruleum inert, and Black Rose, despite it's name is Light aligned (because it causes instant stagnation of Aether). It could be that Ceruleum is Darkness aligned though that's always been like a dark purple. Perhaps black rose just stagnates all aether. Or like you said, it could just be personal preference because it looks cool? From what we're shown it looks like all the purple tech in Dawntrail is lightning aligned.