Valerian. Antoninianus. Rome. 257 AD. 

IMP CP LIC VALERIANVS PF AVG, radiate and draped bust right

PM TR P V COS IIII PP, Emperor seated left in curule chair,
 holding globe and sceptre. 

Göbl 135A; not in RIC (cf 142c with "COS III), or Sear with COS IIII. Rare

Courtesy of Roma Numismatics, Feb, 2010