Red Queen by Victoria Ayeyard

This is a world divided by blood – red or silver. The Reds are commoners, ruled by a Silver elite in possession of god-like superpowers. And to Mare Barrow, a seventeen-year-old Red girl from the poverty-stricken Stilts, it seems like nothing will ever change. That is, until she finds herself working in the Silver Palace. Here, surrounded by the people she hates the most, Mare discovers that, despite her red blood, she possesses a deadly power of her own. One that threatens to destroy the balance of power.