THE ABUNDANT AND complex coins of Diocletian document a period of profound change in Roman history.

In November 284, Roman soldiers escorting the ailing emperor Numerian's coach across Anatolia smelled a foul odor. When they opened its curtains, they found the emperor had been dead for some time. Suspicion fell on Lucius Flavius Aper, the Praetorian Prefect. Diocles, commanding the imperial bodyguard, accused Aper of murdering the emperor and executed him on the spot. The legions immediately proclaimed Diocles as emperor, who renamed himself Diocletianus-usually written in English as .

A tough soldier of humble origin from Dalmatia (the coastal region of modern Croatia), Diocletian would rule for 20 years, ending the chaotic that had tormented the empire for five decades. Realizing that the Roman Empire had become too large for one man to manage, he made his trusted friend Maximianus co-emperor in the West, ruling from Trier in Germany and later from Milan in Italy. Diocletian himself ruled in the East, establishing his capital at Nicomedia (modern Izmit, Türkiye). To ensure a smooth succession, each emperor later appointed a junior colleague (designated as Caesar) in a system that historians call the Tetrarchy[2]. Maximian chose Constantius Chlorus as his junior colleague, while Diocletian chose Galerius, sealing the deal by giving Galerius his daughter in marriage.

Roman soldiers during this era expected to be paid in gold. Although the purity of the metal was maintained, the weight of the gold aureus declined sharply during the second half of the third century CE, becoming so inconsistent that the coins traded by weight. Early in his reign, Diocletian issued aurei of 6.5 grams at a standard of 50 to the 12-ounce Roman pound. This was later reduced to a standard of 60 to the pound (5.3 grams). One source (Sear, 79-89) lists 97 different aurei coins in the name of Diocletian alone, and additional joint issues that depict him and his co-emperor Maximian.

The emperor's stern portrait features a laurel wreath, a short beard, and a military haircut. The reverse typically bears the standing figure of Diocletian's patron deity Jupiter with an eagle and the inscription IOVI CONSERVATORI AVG ()[3]. An example graded brought $16,000 in a 2023 U.S. auction.

To read the complete article, see:
The Great Reformer: The Coins of Diocletian(https://coinweek.com/diocletian-coins-the-great-reformer/)