The swaggering imagery displayed on the coin was already famous in antiquity. In the second century AD, the Roman historian Cassius Dio wrote: "Brutus stamped upon the coins which were being minted in his own likeness and a cap and two daggers, indicating by this and by the inscription that he and Cassius had liberated the fatherland." Although 60 surviving examples of the silver version are known, including several in the museum's coins and medals collection, there were only believed to be two in gold. Experts now believe one of those is a fake, making the newly displayed treasure unique.
Source: The Guardian UK, New York Times.