Countermark

https://rpc.ashmus.ox.ac.uk/countermark/1357 
GIC
CAE
rectangular 
11.5 x 6.5 mm 
there is no comparable cmk in Martini-Pangerl 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 4247a Show 4247 18 1