Select Mint Letter or Name to see individual Mint details

When Diocletian re-organised the coinage, he also changed the way the mints worked by requiring each mint to engrave their coins with an identifiable mint-mark, and also letters or marks to indicate the individual workshops (officina) within the mints. Each mint-mark from Diocletian onwards consists of a group of letters identifying the mint (normally in the exergue) and usually (but not always) letter(s) and/or mark(s), sometimes in the exergue, sometimes in the field, which identify the workshop. In the West, workshops were numbered either in Latin numerals I, II, III or in the initial letters of Latin ordinals, P(rimus), S(ecundus), T(ertius). As latin would have had difficulty in distinguishing between S(ecunda) and S(exta) and between Q(uarta) and Q(uinta), in the West mixed Greek and Latin systems were used to give P(rima), B, T(ertia), Q(uarta), E, and S(exta). Western mints sometimes used the Greek system at varying times.

Where the workshop letter was in the exergue, this was normally placed alongside the mint name, either before of after it, so, for example, the mint-name for Sirmium, SIRM, could be shown as ASIRM, indicating the first workshop; SMK, Cyzicus, could be shown as SMKA, for the first workshop at that mint. Workshop letters or symbols also appear in the field and deciphering them is not always straightforward, as this example of a Diocletian Follis shows. The mint name ALE (Alexandria) appears in the exergue, but there are three letters in the field, S,P and Δ. One may indicate the workshop, while the other two are possibly some sort of quality control markings.

Letters also appear with the mint signature that are not workshop designations. These are: P = Pecunia, e.g. PLON - London SM = Sacra Moneta, e.g. SMANT - Antioch.