Countermark

https://rpc.ashmus.ox.ac.uk/countermark/709 
GIC 583
C·B in square punch of 8 mm
Colonia Berytus 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC IV, 6756 (temporary) Show 2236 6 4.3
RPC III, 3855 Show 3855 17 3