A nice piece. Patina, tarnish.
Obverse: bust of the emperor in radial crown, armor and paludamentum, to the right, in the rim legend:
IMP C VAL DIOCLETIANVS P F AVG;
Reverse: Emperor receives Victoria from Jupiter, surrounded by legend:
IOVI CONSERVATORI AVGG, in Gamma field, in segment XXI;
Silver coinage, diameter 22 mm, weight 4.31 g, axis 6 h.