Aureus

The aureus was the principal gold denomination of the Roman monetary system from the late Republic through the early fourth century AD. It was introduced as a regular issue during the Second Punic War and became a standard denomination under Julius Caesar and Augustus. The weight started at roughly 8 grams under Caesar, was reduced to about 7.3 grams by Nero, and declined further through the third century before being replaced by the solidus under Constantine I. Aurei typically measure 19–21mm in diameter and were struck on broad, carefully prepared flans — the high intrinsic value of the metal demanded precise weight standards. Because gold does not corrode, aurei often survive in exceptional condition compared to silver and bronze issues of the same period. The denomination is identified in standard references (RIC, BMC, Calicó) alongside silver and bronze issues of each reign. For collectors, aurei represent the top tier of Roman coinage — they appear far less frequently than denarii at auction and command prices that reflect both rarity and metal value. Republican aurei, particularly those of the civil war period and the imperatorial issues of Caesar and Brutus, are among the most sought-after coins in all of ancient numismatics.