User blog comment:DiegoAnime3000/Black is for Polarity/@comment-15145664-20140110234404/@comment-3146930-20140112011237

Maybe, but that would still be inaccurate. Pyrrha's Semblance takes the form of a Black-aura around her hand (not to be confused with her Aura), but that is just how her Semblance operates and has nothing to do with gravity. Maybe just Black-Dust has to do with Gravity and the fact that it shares the same color as Pyrrha's Semblance is a coincidence. Also, I think in the DVD commentary, they mentioned doing an episode about Aura~Semblance~Dust; but they could have been joking.