Countermark

https://rpc.ashmus.ox.ac.uk/countermark/1514 
GIC
bearded head (Septimius Severus?), r. (circular punch)
circular 
7.5 mm 
on a coin of Nicaea (Bithynia) 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC V.2, — (number not assigned), type ID 64239 Show 801 1 5.2