Jeweler's Rouge is a substance widely used in Avalon to polish jewels or gems. In the distant past, Corwin after polishing a bracelet he had gotten for Deirdre, discovered that this substance was combustable in Amber. Seeing how normal gunpowder does not ignite in Amber, this was a excellent substitute. The Guns of Avalon, Corwin turns the jeweler's rouge into gunpowder and assembles an army in hopes of taking the throne in Amber.