Diadumenian as Caesar (217-218).     AR Denarius. Rome mint, 217 AD.   Obv.    M OPEL ANT DIADVMENIAN CAES. Bare-headed, draped and cuirassed bust right.        Rev.   PRINC IVVENTVTIS. Diadumenian standing left, holding baton and sceptre; on right, two standards surmounted by eagle and wreath.     RIC IV  Macrinus 108.     2.94 g.   19.00 mm.      R.  Rare. Light tone. Nice example fully centred.    Good VF.