GIC 13
laureate head of Heracles, bearded, r.
oval or circular 
8 x 6.5 mm 
GIC had Heracles(?) - subsequent example show it is Heracles. Martini-Pangerl 99, noted as applied to coinage in Moesia & Thrace 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 1957 Show 1957 19 1
Show 176