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 5915 2 6
RPC VI, 6117 (temporary) Show 5924 5 6
RPC VI, 6127 (temporary) Show 5922 3 6
RPC VI, 6123 (temporary) Show 5920 1 6
RPC VI, 6126 (temporary) Show 5930 17 6
RPC VI, 6111 (temporary) Show 5913 4 6
RPC VI, 6116 (temporary) Show 5921 2 6
RPC VI, 6117 (temporary) Show 5924 17 6
RPC VI, 6113 (temporary) Show 5927 1 6
RPC VI, 6121 (temporary) Show 5916 2 6
RPC VI, 6117 (temporary) Show 5924 4 6
RPC VI, 6125 (temporary) Show 5926 1 6
RPC VI, 6113 (temporary) Show 5927 3 6
RPC VI, 6112 (temporary) Show 5914 1 6
RPC VI, 6117 (temporary) Show 5924 7 6
RPC VI, 6117 (temporary) Show 5924 6 6
RPC VI, 6114 (temporary) Show 5931 2 6
RPC VI, 6126 (temporary) Show 5930 9 6
RPC VI, 6117 (temporary) Show 5924 18 6
RPC VI, 6117 (temporary) Show 5924 20 6
RPC VI, 6121 (temporary) Show 5916 4 6
RPC V.3, — (number not assigned), type ID 80677 Show 153 1 5.3
RPC VI, 6126 (temporary) Show 5930 19 6
RPC VI, 6116 (temporary) Show 5921 5 6
RPC VI, 6117 (temporary) Show 5924 21 6
RPC VI, 6118 (temporary) Show 5929 2 6
RPC VI, 6121 (temporary) Show 5916 6 6
RPC V.3, — (number not assigned), type ID 80860 Show 191 2 5.3
RPC V.3, — (number not assigned), type ID 80821 Show 184 1 5.3
RPC V.3, — (number not assigned), type ID 81053 Show 188 2 5.3
RPC V.3, — (number not assigned), type ID 81236 Show 189 1 5.3
RPC V.3, — (number not assigned), type ID 81053 Show 188 1 5.3
RPC V.3, — (number not assigned), type ID 80720 Show 78 2 5.3
RPC V.3, — (number not assigned), type ID 80701 Show 86 1 5.3
RPC V.3, — (number not assigned), type ID 81174 Show 81 1 5.3
RPC V.3, — (number not assigned), type ID 80700 Show 89 1 5.3
RPC V.3, — (number not assigned), type ID 81000 Show 91 1 5.3
RPC V.3, — (number not assigned), type ID 80916 Show 92 2 5.3
RPC V.3, — (number not assigned), type ID 80914 Show 94 1 5.3
RPC V.3, — (number not assigned), type ID 81237 Show 192 1 5.3
RPC V.3, — (number not assigned), type ID 80675 Show 150 2 5.3
RPC V.3, — (number not assigned), type ID 80675 Show 150 6 5.3
RPC V.3, — (number not assigned), type ID 80712 Show 151 1 5.3
RPC V.3, — (number not assigned), type ID 80696 Show 162 2 5.3
RPC V.3, — (number not assigned), type ID 83833 Show 93 1 5.3
RPC V.3, — (number not assigned), type ID 80675 Show 150 5 5.3
RPC V.3, — (number not assigned), type ID 87002 Show 88 1 5.3
RPC VI, 6111 (temporary) Show 5913 6 6
RPC VI, 6117 (temporary) Show 5924 28 6
RPC VI, 6115 (temporary) Show 5915 3 6
RPC V.3, — (number not assigned), type ID 86045 Show 154 2 5.3
RPC V.3, — (number not assigned), type ID 80699 Show 160 6 5.3
RPC V.3, — (number not assigned), type ID 91431 Show 165 1 5.3
RPC V.3, — (number not assigned), type ID 81174 Show 81 2 5.3
RPC VI, 6126 (temporary) Show 5930 23 6
RPC VI, 6127 (temporary) Show 5922 2 6