Watch List notes:

The Roman Empire

Postumus, 259 – 268. Aureus, Colonia Agrippina 263-264, AV 5.17 g. POSTVMVS – PIVS AVG Laureate head r. Rev. QVINQVENNALES POSTVMI AVG Victory standing r., l. foot on cuirass, writing X on shield set on her knee. C 308. RIC 34. Schulte 86. Calicó 3773.
Very rare and in exceptional condition for the issue. A portrait of enchanting beauty in
the finest style of the period. Virtually as struck and almost Fdc

Ex Leu 52, 1991, Distinguished American Collector, 249 and Tkalec 7 May 2006, 224 sales.
In AD 260, the Roman legions stationed in Gaul ceased to recognize the authority of Gallienus and proclaimed Postumus, an obscure commander of possible Germanic (Batavian) origin, as their preferred emperor. This event marked the creation of a separate Gallic Empire that survived as a distinct political entity until it was reabsorbed into the Roman Empire by Aurelian in AD 274. Postumus was immediately recognized in Gaul and the two Germanias, but by AD 261 his separatist empire had grown to include Britannia, Hispania, and Gallia Narbonensis as well. The empire survived and grew under Postumus through the strong support of the Gaulish nobility and the continued weakness of Gallienus in Rome.
This aureus celebrates the quinquennalia (five-year anniversary) of Postumus' reign as indicated by the reverse legend with the number X that Victory inscribes on a shield looking forward to his decennalia. Indeed, Postumus had much to celebrate at his quniquennalia. In five years he had not only managed to restore peace and security to the western provinces in the face of threats by the Franks and other Germanic peoples, but he had also defeated an attempt by Gallienus to forcibly restore the Gallic Empire to Roman control.
The superb quality of the engraving and the full weight of the coin illustrate the level of success that Postumus enjoyed at the five-year mark. He controlled the mines of Hispania and Britannia, thereby giving him access to the precious metals needed for a coinage of quality. Likewise, the peace that his early reign established allowed for the careful work of a skilled artist required to create such a wonderful obverse portrait. War debases all things, including the weight of coins and their artistry.