"Counterfeiting seems to have been on a fairly small
scale until until the reform of 318, but that reform is something of a watershed in late
Roman monetary
history.
Hoards tend to end or begin with it and this is a fact which must point to a legislative background obscure to us: perhaps the earlier issues were demonetized, becoming
pecuniae vetitae, to adopt the expression of a later imperial edict ", George
Boon, 'Counterfeit Coins in
Roman Britain'
in Coins and the Archaeologist (2nd ed.),
London, 1988.
The edict referred to above is preserved in the
Codex Theodosianus IX, 23.1 which refers to the reform of AD 348 and the concurrent demonetization of existing coins, which are therein called
pecuniae vetitae ("prohibited
money"). We know that something happened in 318 to cause hoarding on a large
scale and a severe empire-wide shortage of small change which in turn stimulated counterfeiting on an epidemic level. While Brunn in
RIC VII does not mention demonetization he does refer to the reform of 318 as a "barrier" stating "except for stray pieces the
hoards either close immediately before the
Victoria laetae coinage or start with that coinage" (p. 13). Brunn then explains that there is no extra-monetary explanation for the "high number of
hoard burials in 318-19" such as political strife or invasion and so attributes the cause rather nebulously to "monetary conditions". We can't be certain exactly what happened since, as
Boon notes, the "legislative background" is lost to us. We do know, however, from the
Codex Theodosianus that in 348 demonetization indeed
was a factor in a similar episode of reform followed by epidemic counterfeiting.
I really can't agree with your notion that a new
reverse type would not be enough to separate the old from the new. I assure you that if tomorrow the US government announced that only Washington quarters with state reverses were valid from that point on, I would be most careful not to accept any with
eagle reverses! I don't think I would find it so difficult to separate the wheat from the chaff.
--Dave