The jewelry was given to Callas by her husband, industrialist Giovanni Battista Meneghini, who married the diva in 1949. She later left him for shipping magnate Aristotle Onassis.
The jewels, which were displayed in New York, London, Paris, Rome, Milan, and Lugano before going to auction, were left to a friend, who remains anonymous, when Callas died in 1977.