Claim: Gemma di Vergy (premiered 26 December 1834) is an Italian tragic opera based on Charles VII chez ses grands vassaux by Alexandre Dumas père.
Evidence: Gemma di Vergy is an 1834 tragedia lirica (tragic opera) in two acts by Gaetano Donizetti from a libretto by Giovanni Emanuele Bidera. It is based on the tragedy Charles VII chez ses grands vassaux (Charles VII and His Chief Vassals) (1831) by Alexandre Dumas père, which was later to become the subject of the opera The Saracen by the Russian composer César Cui. Gemma di Vergy was first performed on 26 December 1834 at the La Scala, Milan.