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 AVG;
Reverse: Emperor receives Victoria from Jupiter, surrounded by legend:
CONCORDIA MILITVM, in HB field;
Bronze, diameter 19 X 21 mm, weight 2.61 g, axis 12 h.