Greek coin dating
Gradually, following the financial excesses of the Punic Wars, the weight of coins was reduced, as was the metal content of the bronze bars. Appearing for the first time was the silver denarius (pl.
Due to financial necessity, gold coins (aurei) were also minted, a rare event not to be repeated until the 1st century BCE. denarii), a coin that would be the principal silver coin of Rome until the 3rd century CE.
As Rome expanded and took ever more treasure from her enemies silver began to replace bronze as the most important material for coinage.
This was especially so following the acquisition of the silver mines of Macedonia from 167 BCE, resulting in a huge boom in silver coins from 157 BCE. 141 BCE the bronze was devalued so that now 16 were equivalent to one denarius.
One solution was to reduce the weight and or the metal content of coins and so increase the possible money supply.
Nero did this in 64 CE (reducing gold content by 4.5% and silver by 11%) as did Commodus, Septimius Severus and Caracalla, who produced the antoninianus which perhaps had the face value of two denarii whilst only really being worth nearer one and a half.
From Aurelian attempts were made to improve the situation with coins being stamped to indicate their metal content: XXI or KA for 5% silver and XI or IA for 10 %.
In 293 CE Diocletian continued the reforms by guaranteeing the gold content of the aurei at 60 to a pound (later renamed the solidus and which would actually outlast the empire itself), minted a new pure silver coin and a part silver bronze coin, the nummus (worth 1/7200 of a solidus).
The silver denarius continued as before (now valued 84 to the pound) and the gold aureii were valued at 25 denarii each and 41 to the pound (7.87 g).Hundreds of individual cities across the empire also minted their own coins and the forms of smaller denominations, in particular, were left to local authorities but in general all of these provincial varieties were convertible to Roman coin values.