I wouldn't worry about how round it is. There seemed to be a lot more care put into preparing flans in the 1st century A.D. than in, say, the 3rd century. I don't know enough about countermarks to have an opinion. In case it's helpful--I have my doubts, considering its condition--here's a similar coin from my collection for comparison: Agrippina Senior Wife of Germanicus Bronze Sestertius Rome mint, A.D. 50-54 Obv: AGRIPPINA M F GERMANICI CAESARIS Rev: TI CLAVDIVS CAESAR AVG GERM P M TR P IMP, encircling SC RIC (Claudius) 102 34mm, 26.1g.
I agree. In contrast to the squarish flans on sestertii of the Antonine period and beyond, Julio-Claudian sestertii are typically round. Here's my example, purchased at Forvm in 2003:
I find the flanof the OP coin a little too thick (could it have been hammered?), there is unusually little wear on the letters, and the centring is almost too perfect for me.
It is a very good looking coin. This is not to say it is genuine - there are some scary fakes coming out of eastern Europe and some of them have convincing (to me) green patina. Others look spray-painted. If this is fake, it was prepared with some care. I recently got an example of this countermark on a Claudius sestertius - it came from Serbia, so I suppose it could be a fake, but it is a lot uglier than the fakes I'm seeing all over eBay. As RC notes, the countermarks are generally in much better condition than the host - countermarks are often deeply recessed, and, of course, more recent than the host. When I was researching this countermark, I found some references to the NC being joined in the countermark - which seems to be the case with the OP. See my attribution notes below. Claudius Æ Sestertius CM for Nero or Nerva (c. 41-54 A.D. host) [TI CLAVDIVS CAES]AR A[VG PM TR P IMP (P P?)], laureate head right / [SPES AVGVSTA], SC in exergue, Spes walking left, holding flower and lifting hem of skirt. RIC 99 (no PP) or RIC 115 (PP) (24.36 grams / 32 mm) Countermark: NCAPR (11 mm x 3 mm rectangle). NC is joined (Italy) Pangerl 60. "Nero Caesar Aug. Populo Romano" "Nummus Caesare Augusto Probatus" "Nero Caesar Augustus Probavit" “Nerva Caesar Augustus Probavit” “Three distinct production centers can be identified for this issue, in Spain, Gaul, and Italy. The Italian type is distinguished by...joining of the letters NC at the base." CNG's Dec 2018 Elec. Auction 434
I try to avoid offering opinions on coins based on photographs - there are so many opportunities for “enhancement” of them these days - but this coin is so interesting that I cannot resist. The NCAPR countermarked issue is described as “very hard to come by” in many sales catalogs, etc. The strike appears to be correct, but the flan thickness appears to be unusually thick in the photograph you included. One of the answers regarding genuineness lies in the weight of the coin. Mattingly lists this coin in BMCRE, vol I, Claudius, No. 222 with a weight of 27.34 gm. What is the weight of the coin you depict? The lettering appears to be correct to me on your coin and the patina also looks appropriate.The countermark also looks correct - they usually are much sharper than the lettering on the “as minted” coins. Here is the example of this coin in my collection: Agrippina the Elder, Sestertius, BMCRE vol. 1 (Claudius), No. 222, AD 42-54, 25.2 gm. (Countermarked NCAPR and with partial legend obliteration). ……… RIC I (Claudius) No. 102, AD 42-54, 25.2 gm. Obverse depiction: Agrippina the Elder, draped bust facing right, hair in long plait down back Inscription: [AGRIPPINA] M F GERMANICI CAES[ARIS] Reverse depiction: [Large SC centered] Inscription: [TI CLAVDIVS] CAESAR AVG [GERM P M TR P IMP P P] NCAPR countermark in incuse rectangle above SC Agrippina the elder was the daughter of Agrippa and Julia (the daughter of Augustus). She married Germanicus, the brother of Claudius, and was the mother of Caligula. Please do reply with the weight of your coin - it is if great interest to me.
Is (or was) that your coin @Herodotus? The weight the owner lists (?) is within the correct range for this issue. If that is the case, I would say this coin could be genuine. (Edited).
No, it is not my coin. It is currently on auction offer on eBay. It also caught my eye, before this thread having been posted. For those interested, here is a thread discussion from earlier this year on this board concerning the NCAPR countermark. https://www.cointalk.com/threads/ncapr-countermark-on-roman-coins.354818/#post-4103739