Diocletian. AD 284-305. AR argenteus, 2.88 g. Cyzicus, struck ca. AD 294-295. 

DIOCLETI-ANVS AVG, laureate head right.
VICTORIA SARMATICA, the tetrarchs sacrificing over a tripod altar before a six-turreted enclosure.

Mintmark CM.
RIC VI, 5a; RSC 490b. 

With permission of Freeman & Sear Mail Bid Sale 12, lot 600, Oct. 2005.