For the next six decades, "The Veiled Nun" was listed as a copy of a bust by an unknown artist. This attribution was changed to the Milanese sculptor Giuseppe Croff (1810-1869) in 1939, when a patron pointed out a similarity with an engraved illustration of a bust by Croff in a catalogue of the 1853 New York World’s Fair. The Croff attribution remained until 2012 when the curator staff looked at a copy of the catalogue and noted significant differences between the works (the actual bust attributed to Croft cannot be located). Further analysis by experts led to a new attribution of an unknown commercial workshop in Rome.