Countermark

https://rpc.ashmus.ox.ac.uk/countermark/1525 
GIC
?, 'vase' or 'cantharos' in circular serrated border
circular 
6 mm 
differs from GIC 485 as has indented border to the punch 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC III, 681 Show 681 3 3