Some facts: Under the reign of Tiberius in 14 AD a Roman silver Denarius weighed 3.9 grams and was 97-99% pure silver. But in 148 AD a Denarius weighed 3.41 grams of 83.5% pure silver. By 241 AD a denarius weighed the same 3.41 grams but of only 48% pure silver. That means since my Tiberius denarius weighs more AND has twice the purity of the post 241 AD denarii that 1 Tiberius denarius is worth a little more than 2 denarii from post 241 AD. So let’s say I’m an Ancient Roman living in 250 AD. I want to buy a denarius worth of bread. Would I get more bread if I used a denarius from the reign of Tiberius than if I used one minted recently with much lower silver content? I am curious how merchants & people in general dealt with having several different kinds of denarii with all of them having different amounts of silver? Did they have to figure out the silver content of every coin? Or did Gresham’s Law force everyone to use the most debased denarii they had and keep the good ones with more silver for themselves?
By 250s there were two silver coins in circulation, denarius and the much more common antoninianus (which were mostly minted from the recalled denarii), and the later is worth 1.5 times more than a denarius, doesn't matter if the denarius is worth more in silver, the government established the value and the people had to follow it like we are doing with fiat currency. However it wouldn't have stopped some enterprising individuals to hoard good quality silver coins for long term value, like today's silver stackers, or some merchants taking them away from Rome where the coins are worth it's value in metal. By the time of Gallienus (250s), antoninianus was nothing but a copper coin coated with a thin wash of silver, yet it still would've had the same purchasing power of a denarius from the 1st century. A denarius has the emperor wearing a laurel wreath, while an antoninianus has him wearing a radiate crown, and that's how people distinguished the coins. For example here is an ant of Aurelian compared to his denarius (one of the last denarius denomination ever minted) (270-275 AD). Even though they're both copper, I'm sure the ant would've bought more than the denarius!
So then if it doesn’t matter that the denarius is worth more in silver (3.9g nearly pure silver) then that means it would’ve made more sense to a Roman back then to hoard them for bullion. Because silver was accepted almost everywhere so they’d get more value selling it as silver bullion rather than try to buy things with it. Like a Morgan Dollar today. Even a common one in Poor condition. You wouldn’t spend it on a candy bar because the silver value of it alone is worth more than the $1 face value.
Probably the same way we did in the late 60's early 70's when there were 90%, 40% and copper nickel clad coins in circulation. You accepted any or all of them at face value and then did you best to only spend the copper nickel clad ones while you kept the silver ones for yourself. I think we can fairly safely assume that whenever a new debased denarius was issued, the older higher fineness or weight ones would quickly disappear from circulation.
