Countermark

https://rpc.ashmus.ox.ac.uk/countermark/640 
GIC 513
Α•Κ
rectangular 
5.5 x 2.5 mm 
meaning of the letters is uncertain. Sometimes on reverse. Unlike GIC 334 (eagle) 513 is not found on the coins od Severus Alexander and was therefore the earlier of the two. 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC VI, 6115 (temporary) Show 5894 2 6
RPC VI, 6117 (temporary) Show 5903 5 6
RPC VI, 6127 (temporary) Show 5901 2 6
RPC VI, 6123 (temporary) Show 5899 1 6
RPC VI, 6126 (temporary) Show 5909 17 6
RPC VI, 6111 (temporary) Show 5892 4 6
RPC VI, 6116 (temporary) Show 5900 2 6
RPC VI, 6117 (temporary) Show 5903 17 6
RPC VI, 6113 (temporary) Show 5906 1 6
RPC VI, 6121 (temporary) Show 5895 2 6
RPC VI, 6117 (temporary) Show 5903 4 6
RPC VI, 6125 (temporary) Show 5905 1 6
RPC VI, 6113 (temporary) Show 5906 3 6
RPC VI, 6112 (temporary) Show 5893 1 6
RPC VI, 6117 (temporary) Show 5903 7 6
RPC VI, 6117 (temporary) Show 5903 6 6
RPC VI, 6114 (temporary) Show 5910 2 6
RPC VI, 6126 (temporary) Show 5909 9 6
RPC VI, 6117 (temporary) Show 5903 18 6
RPC VI, 6117 (temporary) Show 5903 20 6
RPC VI, 6121 (temporary) Show 5895 4 6
RPC V.3, — (number not assigned), type ID 80677 Show 150 1 5.3
RPC VI, 6126 (temporary) Show 5909 19 6
RPC VI, 6116 (temporary) Show 5900 5 6
RPC VI, 6117 (temporary) Show 5903 21 6
RPC VI, 6118 (temporary) Show 5908 2 6
RPC VI, 6121 (temporary) Show 5895 6 6
RPC V.3, — (number not assigned), type ID 80860 Show 188 2 5.3
RPC V.3, — (number not assigned), type ID 80821 Show 181 1 5.3
RPC V.3, — (number not assigned), type ID 81053 Show 185 2 5.3
RPC V.3, — (number not assigned), type ID 81236 Show 186 1 5.3
RPC V.3, — (number not assigned), type ID 81053 Show 185 1 5.3
RPC V.3, — (number not assigned), type ID 80720 Show 76 2 5.3
RPC V.3, — (number not assigned), type ID 80701 Show 84 1 5.3
RPC V.3, — (number not assigned), type ID 81174 Show 79 1 5.3
RPC V.3, — (number not assigned), type ID 80700 Show 86 1 5.3
RPC V.3, — (number not assigned), type ID 81000 Show 88 1 5.3
RPC V.3, — (number not assigned), type ID 80916 Show 89 2 5.3
RPC V.3, — (number not assigned), type ID 80914 Show 91 1 5.3
RPC V.3, — (number not assigned), type ID 81237 Show 189 1 5.3
RPC V.3, — (number not assigned), type ID 80675 Show 147 2 5.3
RPC V.3, — (number not assigned), type ID 80675 Show 147 8 5.3
RPC V.3, — (number not assigned), type ID 80712 Show 148 1 5.3
RPC V.3, — (number not assigned), type ID 80696 Show 159 2 5.3
RPC V.3, — (number not assigned), type ID 83833 Show 90 1 5.3
RPC V.3, — (number not assigned), type ID 80675 Show 147 5 5.3
RPC V.3, — (number not assigned), type ID 87002 Show 85 1 5.3
RPC VI, 6111 (temporary) Show 5892 6 6
RPC VI, 6117 (temporary) Show 5903 28 6
RPC VI, 6115 (temporary) Show 5894 3 6
RPC V.3, — (number not assigned), type ID 86045 Show 151 2 5.3
RPC V.3, — (number not assigned), type ID 80699 Show 157 6 5.3
RPC V.3, — (number not assigned), type ID 91431 Show 162 1 5.3
RPC V.3, — (number not assigned), type ID 81174 Show 79 2 5.3
RPC VI, 6126 (temporary) Show 5909 23 6