Countermark

https://rpc.ashmus.ox.ac.uk/countermark/810 
GIC 689
Φ? or N?
circular 
2.5 mm 
GIC had Φ? RPC had Φ or N? 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 2811 Show 2811 1 1
RPC I, 2811 Show 2811 2 1