Countermark

https://rpc.ashmus.ox.ac.uk/countermark/779 
GIC 654
monogram PHR
Phr(ygia)? Rectangular punch 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 1656 Show 1656 63 1
RPC I, 1656 Show 1656 68 1
RPC I, 1657 Show 1657 21 1
RPC I, 1659 Show 1659 6 1