CNG ebay - Diocletian, under Carausius! AE Ant.
$178.50
11/17/99,

 Diocletian. 284-305 AD. Æ Antoninianus (4.46 gm). Struck under
 Carausius, circa 290-293 AD. "C" mint in Britain. IMP C C VAL
 DIOCLETIAN P AVG, radiate and cuirassed bust right / PAX A-VGGG,
 Pax standing left, holding branch and vertical sceptre; S-P/C.
 RIC V pt. 2, 21 var. VF, light porosity. Very Rare! 717246

 Carausius opened new mints in London and Colchester and even 
anticipated Diocletian's currency reform by striking denarii of 
good silver, the first such coins to be seen in generations. The range 
of types is remarkable and it is obvious that the emperor clearly 
perceived the propagandistic value of the coinage and involved himself
 personally in the messages to be broadcast to his subjects. This
 coin was struck in the name of Diocletian (in Carausius' eyes a
 peer), and by its legend and type presents a conciliatory message
 to his 'imperial colleagues'. The joint-reign issues were 
important for bolstering public support within Britannia rather 
than legitimizing his claim to rule for those outside of his realm).