I found a picture in an old art book which was a portrait of a man holding a coin. Hans Memling, Man Holding a Roman Coin, painted around 1480 A closeup of the coin: The coin has been identified as a sestertius of Nero struck in Lyons. The coin's obverse legend appears close to "NERO CLAVD CAESAR AVG GER P M TR P IMP PP" and there are around ten coins in the Roman Imperial Coins catalog matching this one. The painting is in the Royal Museum of Fine Arts in Antwerp which produced the above public domain photograph
There's also a painting by Sandro Botticelli of a man holding a medal of Cosimo de Medici (in the Uffizi in Florence):