All That Glitters, Paperback/Allison Strom

Emily and Adriane have one thing that Kara does not: a magical gem. But when Kara finally finds a magical stone of her own, a diamond unicorn horn (often called the unicorn jewel), it brings more trouble than anyone can handle. Pesky dragonflies start showing up everywhere and new Detrimental warn of danger. While trying to use the mystical jewel to make her hair stop growing longer uncontrollably, her hair turns rainbow-colored (See the front of All That Glitters). Worse, a band of terrifying monsters stalk Kara. That and signs of a sorceress keep appearing before Kara All these creatures come from another world. And all want something from her. Finding out may take Kara, Emily, and Adriane a step closer to Avalon, the essential source of all magic. But it may also cost one of them her life.