Now, to get closer to what we see on the coins, I've grafted the profile
head onto both the above seen from front/back shots, and truncated them just below the shoulder so we no longer have the pose clue of the arms.
Finally a couple of Constantine coins from my
collection to illustrate these. Hopefully it's obvious whether they are seen from front or back! Note that sometimes the
brooch itself isn't really clear (or maybe not enngraved at all) on the coins, but the position of it (and hence the shoulder position) can be implied from the folds of the cloak leading into it, just as we don't actually need the orange
brooch on Olga to tell the shoulder position because the drapery leading to it tells us where it must be.
Ben