The ancient door ornament was on display at the 'Pompeii and the Greeks' show at the archaeological site's Palestra Grande.
Police believe the theft occurred while the site was open to the public, but the investigation is ongoing.
Director general of the internationally renowned site, Massimo Osanna, expressed his dismay in the wake of the crime.
"In addition to being an act that damages Pompeii and Italy's cultural heritage, it hits me on a personal level, as it was [taken from] an area where I had conducted the excavation myself," Osanna said.
The relic was one of four applied to a replica of an ancient door, and was covered by a protective layer which led Osanna to believe that the suspect must have used some strategy to elude security controls for long enough to remove it.
It was on loan from a museum in the southern city of Potenza, Basilicata, and was insured for 300 euros.
Director of the Basilicata Regional Museum Hub, Marta Ragozzino, expressed solidarity for Osanna, who she described as her “friend and colleague”.
"An act of this nature leaves us incredulous and pained, a gesture that attacks and wounds the cultural heritage that belongs to the community and, when brought to Pompeii, the whole world," Ragozzino declared.
With ANSA
