The inscription L*HER*FLO signifies Lucius Herennius Florus, the name of the owner of the villa at Boscoreale from which the Museum's frescoes come. The stamp was presumably his property and likely served as the official seal of the household used to mark provisions. On the ring in intaglio is a second seal in the form of a winged caduceus, the staff of Mercury, god of commerce. Many such bronze seals have been found in the excavations at the nearby towns of Pompeii and Herculaneum, although stamps with intaglio on both ring and plate are less common.
Milne, Marjorie J. 1930. "A Bronze Stamp from Boscoreale." Bulletin of the Metropolitan Museum of Art, 25 (9): pp. 188, 190.
Lehmann, Phyllis Williams and Herbert Bloch. 1953. Roman Wall Paintings from Boscoreale in the Metropolitan Museum of Art, Monographs on Archaeology and the Fine Arts, Vol. 5. p. 5, fig. 2, Cambridge, Mass.: Archaeological Institute of America.
Bodel, John P. and Stephen Tracy. 1997. Greek and Latin Inscriptions in the USA: A Checklist. p. 200, Rome: The American Academy in Rome.
Bergmann, Bettina. 2010. "New Perspectives on the Villa of Publius Fannius Synistor at Boscoreale." The Metropolitan Museum of Art Bulletin, 67(4): pp. 14, 21, fig. 16.