Crystal and the Stars — Lazette Gifford

Reluctantly leaving behind Brendan's world and their friends, Abby and Tristan follow a path into a darkness lit by diamonds, and find themselves in a place where magic is rarely known, and where evil doesn't always need the impetus of the Kiya to grow strong. But magic draws magic, even here--and they are dropped into the care of a startled ship's captain--who also happens to be a very powerful mage. In order to track down and trap the Kiya, they join forces with an unusual array of allies, including the captain-mage, a smuggler who once held the Kiya--and threw her away--and a prince of questionable character. Meanwhile, Tabor plays at a dangerous game with his demon father and the less than human High Priest, Braith. In an attempt to gain power of his own and free himself from his father's sadistic control, he secretly employs magics that help him stay a step ahead of the others in an attempt to gain the Kiya before Abby and Tristan collect yet another part of the prize.