What Was Wrong With Roman Coinage?

During the third century, the radiate denomination traditionally called the antoninianus had been repeatedly debased. By the later third century, many radiates were largely copper alloy with only a small silver component or silvered surface. Aurelian had already attempted an important monetary reform in the 270s. Diocletian's government went further, creating a reorganized denominational structure across the Empire's expanded network of mints.

Before the Reform: A Debased Radiate

Gallienus Antoninianus, AD 253 to 268, NGC Certified

The heavily debased pre-reform radiate, the problem Diocletian set out to fix, once silver, now essentially bronze. Billon Antoninianus · NGC Certified · from $37.50

View This Coin →

The New Large Bronze: Nummus or "Follis"

The most familiar coin of Diocletian's reform is the large copper-alloy piece that modern collectors often call a follis. Many specialists prefer nummus, because "follis" was originally associated with a bag or sum of coins and its use as the precise ancient denomination name is uncertain. Freshly issued examples were large by the standards of later Roman bronze coinage and carried a small silver component, with surface enrichment helping create a silvery appearance when new.

A famous reverse type reads GENIO POPVLI ROMANI, "To the Genius of the Roman People," usually showing the Genius standing with a patera and cornucopia. It is the signature reverse of the reform coinage, struck across the Tetrarchy's mints for Diocletian and his co-rulers alike.

The Reform Nummus, GENIO Type

Constantius I Bronze Follis, Father of Constantine, c. AD 300

A large Tetrarchic reform nummus of Diocletian's co-ruler Constantius I, the new bronze the reform created. Late Roman Bronze · NGC Certified · from $37.50

View This Coin →

The Argenteus and the Gold

Diocletian also introduced the argenteus, a high-purity silver denomination. Its standard is commonly associated with 96 coins to the Roman pound, a relationship sometimes advertised by the reverse legend or mark XCVI. The argenteus is important because it represented an effort to restore a substantial, reliable silver coin after the dramatic debasement of the third century. It was never as abundant as the large bronze nummus and is considerably less common for collectors today.

Gold continued to play a major role in the reformed system. Diocletian's gold coinage was struck to standards that changed during the Tetrarchic period; it should not be confused with Constantine's later solidus, introduced in the early fourth century and eventually established as the dominant late Roman gold denomination.

The Tetrarchy on Coins

Diocletian's monetary reforms cannot be separated from the Tetrarchy. Diocletian and Maximian ruled as Augusti, with Galerius and Constantius Chlorus as Caesars. Coin portraits often emphasize a deliberately similar, blocky, militarized appearance rather than highly individualized likenesses. That visual language mattered: the message was collective imperial authority, multiple rulers governing different regions while presenting themselves as members of one legitimate system.

Did the Reform Fix Inflation?

Not permanently. Diocletian's reforms reorganized the coinage and produced important new denominations, but Roman monetary problems were tied to taxation, state spending, military costs, prices, metal supply, and political conditions, not merely the designs or weights of coins. His famous Edict on Maximum Prices, issued in AD 301, attempted to impose maximum prices and wages across a huge range of goods and services. It is evidence of the government's concern with rising prices, but it should not be treated as proof that the coin reform simply "failed" in one step. The relationship between late Roman monetary policy, prices, and inflation is more complicated.

What Happened to the Nummus?

The large reformed bronze did not remain large. During the early fourth century its weight was reduced repeatedly, and later Roman copper-alloy denominations became progressively smaller. This is one reason collectors should be cautious about calling every later bronze a "follis." By Constantine's era and afterward, modern size classifications such as AE1 to AE4 are often useful when ancient denomination names are uncertain.

Why Collect Diocletian's Reform Coinage?

Few ancient coin series make an economic reform so tangible. A collector can place a debased third-century radiate beside a large Tetrarchic nummus and an argenteus and see the imperial government's attempt to rebuild the currency. These coins also open the door to collecting the Tetrarchy by ruler, mint, officina, reverse type, or monetary reform.

Diocletian did not permanently solve Rome's monetary problems. What he did was create one of the most ambitious monetary reorganizations of the later Empire. The coins that survive from that reform are physical evidence of a government trying to impose order after the chaos of the third century.

Hold what the greats held.