Countermark

https://rpc.ashmus.ox.ac.uk/countermark/1522 
GIC
ΑΡ monogram (incuse, etched)
incuse 
c. 10 mm high x 8.5 mm wide at base 
Manually etched incuse version of GIC 606 - applied at Antioch. Head of P can be on either side of the A 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 4090 Show 4090 1 1
RPC I, 4090 Show 4090 2 1
RPC I, 4090 Show 4090 7 1
RPC I, 4090 Show 4090 4 1
RPC I, 4089 Show 4089 2 1