I just read Jared Dawber’s comment on First Man in Rome in the latest E-Sylum – actually McCullough is right – the first appearance of the sestertius as a coin was in silver and it was quite small – valued at 2.5 asses or 1/2 a quinarius or 1/4 denarius. The coins were only issued from 211 – 206 BC.

The brass sestertius that Jared refers to and that most of us are familiar with was not introduced until the time of Augustus (around 18 BC). So for the time period which the First Man in Rome discusses, McCullough is perfectly correct – in fact I am very surprised and impressed that she caught a numismatic detail that most numismatists, even those who collect Roman coins, would miss. Yet another reason why the First Man in Rome series is one of my favorite historical novels!"

Mudd is correct that the Roman silver sestertius was first struck c. 211-206 BC. However, it was not "only" issued during that period. It was revived in 91-85 BC by 2 or possibly 3 moneyers. It then disappeared for another 40 years, but was again revived during the period 48-44 BC (the period of McCullough's book), and struck by 12 moneyers. All of these sestertii are scarce or rare, so they were probably not economically significant, but during the Republic and early Empire, the sestertius was widely used for designating sums of money. The sestertius finally became a bronze coin c.38 BC, as part of Antony's fleet coinage.

Douglas Mudd is mistaken that silver sestertii were only issued from 211-206 B.C. See H. A. Seaby, Roman Silver Coins, Vol. I, The Republic to Augustus. Silver sestertii are listed on pp. 3, 7, 12 (44 B.C.), 15 (46 B.C.), 25 (90-89 B.C.), and many other pages.