Countermark

https://rpc.ashmus.ox.ac.uk/countermark/821 
GIC 702
D? (D with hook backwards, at top of D)
circular 
5 mm 
Sometimes on reverse 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 5421 Show 5421 12 1
RPC I, 1555 Show 1555 64 1
RPC I, 1629 Show 1629 16 1
RPC VI, 3534 (temporary) Show 2861 5 6
RPC I, 1636 Show 1636 16 1