Wikipedia page about this book: https://de.wikipedia.org/wiki/Der_Diamant_des_Geisterk%C3%B6nigs

Release date is 2005-04-01

Produced by Delphine Lettau and Mike Pullen

"Der Diamant des Geisterkönigs" by Ferdinand Raimund is a magical farce with songs composed in 1824. When magician Zephises dies, his son Eduard must reach the spirit king Longimanus's palace to claim his inheritance. Eduard faces supernatural trials, including climbing a mountain without looking back, where those who turn are transformed into animals. To receive the most precious treasure—a diamond statue—Eduard must find an 18-year-old girl who has never told a lie, leading him on an unexpected journey of love and discovery. (This is an automatically generated summary.)

Original publication data not identified