Hi Lerian!
Really beautifull coin... And quite
rare! Unfortunately
still missing in my
collection... In
RIC the coin is only listed as
scarce, but in
Hill (which I use mainly because of the more accurate
rarity scale) it is listed as R4! The truth is surely somewhere in between. As you said, the coin is an undated one, however there is a hole serie of dated coins (
Denarii and Antoninianii) with the same or similar
reverse type refering to the
parthian campaign clearly dated to 217 so I do not doubt that this coin belongs to the last year of Caracalla's reign. May I ask you where you were able to buy that coin?
Regards
David