I just picked this one up, which was called "unpublished." While this coin is not listed in RIC, it is not unpublished. RIC even footnotes an example of this type- "Some coins not with star but with dot in exergue, the dot most likely intended for a star." Speck and Huston in Constantine's Dafne Coinage argued that this dot was not meant to be a star, but rather that it was a dot, which correlated with the same mintmark in a gold issue from A.D. 330. I have also had examples from each of the seven officinae that struck these coins, so this mintmark most surely is a separate issue, not to be confused with the star issue. This mintmark, while a bit rare, is more common than you might expect, even though it is not in RIC.
