My first thought was Caracalla
But I believe I can read AVT M AVP in the 8-11 o'clock region
Something like 15 later emperors adopted the name of Marcus Aurelius but in this case I think it is probably the original
A young portrait of Marcus Aurelius
IN GOD WE TRVST ....... all others pay cash !
COGITO ERGO SPVD
I think ...... therefore I yam