It would seem to me that if numismatic marks are considered for addition to Unicode, that hallmarks would be a similar set of symbols that would be as equally desirable as characters. The maker's marks should probably not be encoded, but the assay office marks and purity marks are both standardized and finite. However, it would probably be best to encode them as the symbol where feasible and include a gloss of its usage. Thus for example instead of FRENCH GOLD HALLMARK, the character RIGHT-FACING EAGLE HEAD would be a more appropriate character name for that mark.
