Countermark

https://rpc.ashmus.ox.ac.uk/countermark/1518 
GIC
rectangular 
5.5 x 3 mm 
separarated from GIC 518 as later and with different shaped and larger punch 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC VI, 6268 (temporary) Show 6017 3 6
RPC VI, 6270 (temporary) Show 6022 4 6