Thirteen by M. J. Carey
When Joe Bulmer, a London punk with mild telekinetic powers, discovers a mysterious black pearl which increases his abilities to unbelievable levels, he thinks he's struck it rich. But he soon discovers that the pearl's original owners want it back, as do a terrifying race of alien shape-shifters! Now, with the help of Daksha, a beautiful Asian telepath, Joe must fight to save the pearl from forces who would use it to destroy the Earth!