Countermark

https://rpc.ashmus.ox.ac.uk/countermark/682 
GIC 553
ΝΙΚΟ
incuse 
variable 
often with GIC 782 (Δ) 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC IV, 4338 (temporary) Show 2794 7 4.1
Show 450
RPC IV, 4337 (temporary) Show 2797 8 4.1
RPC I, 1657 Show 1657 56 1