Countermark

https://rpc.ashmus.ox.ac.uk/countermark/748 
GIC 625
ΝΚ monogram (on obverse)
circular 
5.5 mm 
Thessalonica likely but not certain. Nero Caesar? 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 1554 Show 1554 91 1
RPC I, 1554 Show 1554 92 1
RPC I, 1554 Show 1554 93 1
RPC I, 1554 Show 1554 94 1
RPC I, 1554 Show 1554 96 1
RPC I, 2235 Show 2235 40 1
RPC I, 1554 Show 1554 99 1
RPC I, 1554 Show 1554 100 1
RPC I, 1554 Show 1554 101 1
RPC I, 1554 Show 1554 102 1
RPC I, 1554 Show 1554 103 1
RPC I, 1554 Show 1554 104 1
RPC I, 1554 Show 1554 105 1
RPC I, 1554 Show 1554 106 1
RPC I, 1554 Show 1554 108 1
RPC I, 1554 Show 1554 109 1
RPC I, 1554 Show 1554 110 1
RPC I, 1554 Show 1554 111 1
RPC I, 1554 Show 1554 112 1
RPC I, 1554 Show 1554 113 1
RPC I, 1554 Show 1554 114 1
RPC I, 1554 Show 1554 116 1