Killashandra by Anne McCaffrey

This sequel to McCaffrey's Crystal Singer continues the story of Killashandra Ree, a failed musician whose perfect pitch has given her entree to the glamorous but dangerous profession of mining and cutting rare, valuable crystal. She is grateful for a new assignment that takes her off the oppressive crystal world of Ballybran, but when she arrives on Optheria to replace and tune the crystals of a famous organ, she steps into a new adventure.