Countermark

https://rpc.ashmus.ox.ac.uk/countermark/1250 
GIC
Γ and dolphin r.
circular (or slightly oval?) 
9 mm 
only current example on coin of Ephesus 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC V.2, — (number not assigned), type ID 826 Show 3424 4 5.2