Certamente ho trovato qualcosa: Diadumenian, as Caesar, AR Antoninianus. May-July 217 AD. M OPEL DIADVMENIANVS CAES, radiate, draped bust right, seen from behind / PRINC IVVENTVTIS, Diadumenian standing left, holding baton and sceptre, two standards to right. RIC 106; RSC 11a.
217-218 AD, Antoninianius, Rome, 217 AD, 4.37g. C-11 (80 Fr.), BM-82 note. Obv: M OPEL DIADVMENIANVS CAES Bust radiate, draped, cuirassed r., seen from front. Rx: PRINC IVVENTVTIS Diadumenian standing l. holding baton and scepter, two standards behind him topped by eagle and wreath respectively. Very rare denominati