054: Diocletian Sestertius

Diocletian. AD 284-305. Æ Sestertius (24.5mm, 5.16 g, 12h). Rome mint. Struck circa 293(?). Laureate and draped bust right / Jupiter standing facing, head left, holding thunderbolt and scepter. Cf. RIC V 199 corr. (rev. legend) (there described as an As); Cf. RIC V 202 corr. (rev. legend) (there described as a Semis); Peus 417, lot 680 (same dies). Extremely rare, seemingly the 2nd known.

The post-Gallienus 3rd century Roman imperial bronzes are understudied and poorly understood. It was the belief of the authors of RIC volume V that they could divided into 2 denominations: the As and the Semis. They reached this conclusion because they examined lighter coins on smaller flans and heavier examples on broader flans, and all of these coins weigh roughly 4g-8g, which is why the authors thought they were two  smaller denominations. There are a few problems with this, though. There are multiple pairs of coins recorded of the same type with varying weights and diameters; in fact, this very coin and the Peus specimen are one example of this. The Peus specimen weighs 6.43g, which would make it an As, but by weight my coin would be a Semis. I've seen another example with FIDES MILITVM bronzes of Probus in the British Museum. It's been suggested in the case of Probus that there was only one denomination but that it underwent a weight reduction, as similar coins of the next emperors are all lighter, but I don't believe they would continue to use the same dies if this were the case. Regardless, this most likely is not the case for the Peus coin and mine because it appears to have been minted late in the Dyarchy or at the beginning of the Tetrarchy due to stylistic similarity to an unpublished Galerius bronze in the Albert-Ludwigs' University collection (06823). Indeed, the portrait style of pre-reform tetrarchic bronzes vary significantly, which suggests they were minted in several emissions over the years. If this is the case and my coin type is a late example, it's very unlikely a weight reduction occurred. The facts that there are multiple legend break varieties for the IOVI CONSERVAT AVGG type and some have a spread chlamys and some don't further lends credence to this theory. Additionally, it seems that other denominations were minted on an annual basis at this time, such as the Denarius, according to RIC, which seems secure. It would make sense that the bronze denomination would follow suit. It's also possible that these were struck for multiple special occasions, such as the accession of emperors and the quinquennalia of AD 290-291, for example. Another possibility is that these bronzes were minted at the same time but are not all the product of the Rome mint. Other mints such as Ticinum and Lugdunum minted Denarii and Quinarii, so it would not be shocking for these to have been made at multiple mints. Further, it is known that Siscia did strike bronzes for Carinus as Augustus (unpublished, but see Classical Numismatic Group 63, lot 1521), so it's possible that this practice would have continued. If these were struck at multiple mints, however, that would not preclude them from having been struck in multiple emissions. The main problem with this possibility though is matching the styles to a different mint; Rome seems like the best fit for all of them. So, to summarize, it seems likely that all of these coins belong to one denomination and were struck at the Rome mint over the course of several years, perhaps annually, perhaps on special occasion only. The last part to address is perhaps the most fundamental but one that could not be properly explained sooner: the denomination these coins actually are. I believe they must be Sestertii. The Sestertius was one of the most important and iconic denominations struck in the Roman Empire. Its purchasing power made it perfect for daily transactions, and it functioned as the unit of account of the day. The As and the Semis were much less notable. Trajan Decius revived the Semis, but before that it hadn't been minted since Marcus Aurelius, and it wasn't minted by Decius' successors. It's very unlikely that later emperors brought this denomination back, especially since some recorded examples are heavier than the original Semisses were. It's more plausible that these coins are Asses, but not enough. The sole argument in their favor is that the coins are too small to be Sestertii, but they're indeed also too small to be regular Asses; for this to be the case they would have had to undergo a weight reduction. The metrology of these coins does not match any existing denomination, so unless they represent an entirely new one, which is extremely unlikely, they must be a reduced form of a known one, of which the Sestertius is the most likely candidate by far. More research is needed on this fascinating series of coins.

Collection : Coin Collection