Siliqua? Theodosius

The coin is from the Constantinople City Commemorative series. This one is a more scarcer type with the reverse of two soldiers standing between a standard holding a spear and resting their hands on a shield. The legend is GLORIA EXERCITVS. If you clean the reverse a bit we might be able to make out the mint mark and come up with a RIC number.

It does not look silvered and the type is not usually silvered. 20-23 mm is wildly unusual for this type which is typically 17 mm or less. Something is wrong here.

The CONSTANTINOPOLI obverse inscription was used at four eastern mints Heraclea, Constantinople, Nicomedia, and Cyzicus, except for an anomalous piece at Trier.

That feature coupled with the particular treatment of the standard on the reverse, suggested this reverse from Constantinople:




The last ring and bar combination which you are reading as an Ankh may be nothing more than the last combination you see here.

Other features about your coin suggest to me that it was minted at Constantinople. However, the measurements you have given for this piece are all out of proportion for any GE reverse from any mint. If the flan is as large as you say, then there is no reason for any part of the design to be off flan and still closely fit on the opposite side. The die for this type was simply not that big. Examples in my collection on 20mm flans have generous margins all around.

I would respectfully suggest and request that you confirm the figures you gave us.

Okay, that fits. Not sure what kind of online measuring device you are using. Is it something that's part of a digital microscope, or perhaps a screen calipers, or something else entirely? If it is a screen caliper device, then they need to be "normalized" for each image since they are designed to give you screen distance and not image size per se. But maybe that has nothing to do with the tool you have.

Anyway, in addition to the treatment of the standard, the use of drilling to fashion the features of the soldiers, and the obverse decoration of the helmet all lead me to suggest your coin is a Constantinopolis City Commemorative in production from 337-340 at the mint in Constantinople; corresponding to RIC VIII #31 for Constantinople.