I haven't started working on this to attribute yet. But, is it possible that there are die cracks on ancient coins? Was it a similar process? The coin attached appears to have a crack from above the eyebrow to the rim.
I have NEVER seen die cracks / breaks on Ancients! They were ALL perfect minters! Etruria Populonia 3rd C BCE AR 20 As 8.1g Metus Blank HN 152 Etruria Populonia 211-206 BC AR 10 As 20mm 4.21g die brk Lr Male Hd L - Blank
Die cracks are not scarce. Some dies were used even after a large chunk fell out. It is sometimes possible to follow the progress of a crack as it worsened over time. Some periods were hard pressed to make replacement dies so cracks are more common while others have fewer because the damaged die was promptly retired. I suppose some people would consider this a fault others would find increased interest. I like the really severe ones like the Gordian III of Nikopolis below. The reverse die crack is bad enough that the die is bent causing the bottom part to be struck better than the top. I have to wonder how many coins were struck from this die after my coin.
I assume you men the OP coin which I see as a raised line rather than a flan crack but that could be a photo issue. I hope it was not referring to mine which matches this one: https://www.acsearch.info/search.html?id=4358618 Finding a die match to a common Constantine will take some looking but perhaps Inspector43 can comment on whether the line is raised (die) or lower (flan). When lighting coin photos we need to be careful to direct light so raised lines and depressions are distinguished. The Arados fourree below has a fine line die crack across the reverse field. The Aigina stater below has a chunk of die missing.
I did look at mine from enough angles that I am convinced the line is raised indicating a crack in the die. I can try to get some better photos it anyone would like to see them.
