Singreale Chronicles Series by Calvin Miller

A huge diamond with marvelous powers is the sought-after prize in each part of this engrossing fantasy-adventure trilogy, which brings alive through metaphor three biblical events: the Fall of man, war in heaven and the Peaceable Kingdom.

In the land of Ren, Graygill heroes Raccoman and Velissa meet the mystical King Ren, whose knights are locked in a war of betrayal. Many of the knights have left the palace, taking on new and hideous forms, and have challenged Ren's right to rule. Complications arise when the King disappears and his nephew usurps the throne.