User blog comment:VedranTheII/Pretentious Diaries 2: What tricks would you teach your Aura?/@comment-10380701-20150718080559

Runic symbols appearing are high-level Dust sorcery. This was discussed intensely since Volume 1 and it's been agreed upon by some veteran users to be the case. Compare and contrast Roman and Ruby's usage of Dust, which are more simple and primitive in comparison.

In Cinder's case, she didn't change the color of her aura, she switched up the Dust she's using.