It is not very difficult to obtain a grasp on the several popular designations used in the Roman Empire.
Coins from various eras can be differentiated by their sizes or look, as will be covered here.
Like to today, gold, silver, and copper or bronze were the primary metals.
Yet, it should be noted that this is a very difficult topic that causes many people headaches. The Romans experienced periods of recession, depression, and inflation, just as we do today (often more quickly than we do!).
As a result, during the lengthy history of the Empire, many sizes, metals, and values of coins were used.
The discussion of gold coins and silver coins from the fourth century AD will be ignored in what follows because they are uncommon and highly expensive.
The initials AV, AR, and AE, which are frequently encountered in a coin’s description or in a catalog, are the first to cause newcomers difficulty.
They only speak about the metal utilized in the ways depicted in Table 1 below.
Table 1: AV, AR and AE : Metal Designations
| Abbreviation | Latin Word | Translation |
| AV | Aureum | Gold |
| AR | Argentum | Silver |
| AE | Aes | Bronze/C |
Hence, “AE Antoninianus” (commonly shortened to “AE Ant”) refers to a bronze Antoninianus.
A silver denarius is known as a “AR Denarius”.
Many beginning collectors begin with the ordinary bronze pieces from the fourth century, both the follis and AE grades, but eventually move on to the lovely silver and/or the huge copper/bronze pieces from the early third century AD and earlier.
The most popular denominations, the metal from which they were crafted, and the approximate period of their most widespread use are listed in Table 2 below.
The descriptions below are brief.
Table 2: Coin Denominations
| Denomination | Metal Used | In Circulation |
| Denarius | Silver | to c.200 AD |
| As, Dupondius, Sestertius | Bronze/Copper/Orichalcum to c.300 AD | to c.300 AD |
| Antoninianus | Silver/Bronze | 3rd century AD |
| Follis, | AE1-4 Bronze (silver wash) | 4th century AD |
The relationship between coin denominations from the time of the Empire up until the start of the fourth century is summarized in Table 3 below.
Although the values changed over time, as can be seen from the descriptions below, this table will still be accurate for the majority of the Empire’s history (some alterations took place during the Republic era).
As As fractions are uncommon, they won’t be covered here.
Table 3: Relative Coin Values
| Denomination Value | Value |
| Aureus [gold] | 25 silver denarii |
| Antoninianus [silver] | 2 silver denarii |
| Denarius [silver] 16 copper asses | 16 copper asses |
| Quinarius [silver] | 8 copper asses |
| Sestertius [orichalcum] | 4 copper asses |
| Dupondius [orichalcum] 2 copper asses | 2 copper asses |
| As [copper] | 1 |
| Semis [brass] | 1/2 as |
| Quadrans [copper] | 1/4 copper as |
As [AE] : This denomination, which means “unity,” was at first a common unit in Roman coinages.
It was initially pounded around 280 BC.
It was made of pure copper at first, giving it a reddish appearance, but by the end of the third century AD, it had been changed to bronze.
As a result, asses are often smaller than dupondii or sestertii and appear darker than those two species.
It is easier to recognize because the emperor is always depicted with a laurel wreath on his head.
Dupondius [AE] : It was minted during the Roman Republic and had a two ass value.
Since Nero, the emperor has always been depicted wearing a radiating crown, which makes it simple to distinguish from sestertii and asses. It is struck from a bronze alloy called orichalcum, which has a yellowish hue similar to the larger sestertius.
Sestertius [AE] :Together with the denarius, it was first issued as a small silver currency in 211 BC, with an initial value of two and a half asses, or one-fourth of a denarius. But, after 44 BC, it was transformed to a very big bronze coin, with a value of four asses.
The coin was composed of bronze and gradually diminished in size before disappearing in the third century (and was rare).
This coin is larger than the US half dollar (30mm+) and frequently displays amazing detail.
The emperor is always depicted with a laurel wreath, which helps to differentiate it, and it is much larger than the lesser dupondius. Throughout the Empire, it was struck from a bronze alloy called orichalcum, making it look yellowish.
Denarius [silver] : First minted around 211 BC, during Rome’s Second Punic War against Carthage (218-201 BC).
The name of this coin comes from its original face value of ten asses, which was later increased to sixteen asses.
The currency was first minted in exceptionally pure silver, almost 100%, but by the time of Nero, Hadrian, and Commodus, it had dropped to 94%, 90%, 73%, and finally below 50%.
Due to several emperors’ attempts at monetary reform, the amount of silver moved up and down (as it was going down).
After more than 500 years of use, the currency completely disappeared around 296 AD as the silver content sharply dropped starting around 238 AD (Gordian III).
Usually the size of a US dime, denarii feature the emperor wearing a laurel wreath on the reverse.
Antoninianus [silver/bronze] : The name of this denomination, frequently shortened to “Ant,” comes from M. Aurelius Antoninus, also known as Caracalla, who established it in 214 AD.
Unknown is the ancient name.
During the following 80 years, the Antoniniani would continue to exist.
Although this coin was initially worth two denarii and was made of silver, its silver content initially only amounted to roughly 40% and quickly decreased over time.
It evolved into a bronze coin slightly larger than the denarius by the time of Gallienus, with little silver content. Therefore, we can have either an AR or an AE ant.
The coin was restored to its former size and given a thin covering of silver termed a “wash” to restore its silver appearance as a result of Aurelian’s monetary reforms.
Yet, the majority of coins made accessible to collectors will have this silver covering worn away or hardly discernible, giving the impression that the coin is bronze. The price of those with the layer intact is greater.
The Roman numerals XXI, or XX, which stand for 20:1, or 20 parts of bronze to one part silver, are often used on the reverse of the coin to indicate the silver content at its end, which was 5%.
In some mints, primarily Serdicia, the Greek letters KA (=21) were also used for this purpose.
The currency disappeared with Diocletian’s reform of coinage in 294 AD, and for a brief period after, small bronze coins with radiate\sheads of the emperors were minted known as ‘post-reform radiates’ or ‘bronze radiates’.
The silver Antoniniani, which are generally the size of a US quarter, are reduced to dime size and given a bronze appearance for emperors in the late third century.
As seen in Figures 8 and 9 below, they always depict the emperor donning a radiant crown.
Also, as time passes, the busts of the emperors become more stylised and have a lower relief, making them appear more alike.
Follis [bronze] : The follis began life as a very large bronze coin with a silver wash, around the size of a US half dollar, and was first produced by Diocletian in 294 AD.
For the next about fifty years, the coin shrank to denarii size (15mm). Moreover, a coin known as a quarter-follis was produced under Severus II Caesar (306-307 AD) and is smaller than other coins of the era.
Follis was not the name given to this currency in antiquity; it is possible that they were called “nummus” instead.
When they were put in bags for transportation or even disseminated in huge numbers as a “bag unit,” the word “follis” simply means “bag”.
Folles thus start out as huge bronze coins and gradually get smaller until they are around the size of a dime by the middle of the fourth century.
The emperor is always depicted with a low relief stylized bust and a laurel wreath on his head.
Some may have silver traces visible.
There can be no misinterpretation because they were released following the discontinuation of the radiate head Antoniniani.
AE1, AE2, AE3, AE4 [bronze] : Finally, we reach a time period in the middle of the fourth century during which the currency denominations are unknown (or there is a lot of disagreement).
However, to prevent confusion, most collectors prefer to use the size scale provided in Table 4 below for these coins. Some collectors will refer to these coins as Centenionalis, Half-Centenionalis, or Majorina.
Typically, the emperor is depicted with a laurel crown on his head.
Constantius II and Honorius, for instance, are remarkably similar and have low profiles, making it challenging to distinguish between them.
These scales should not be confused with the Greek bronze coin and Roman provincial coin classification systems, where a coin’s designation as AE17 indicates that it is 17mm in diameter. Then, AE1 would be quite small.
Moreover, the coins may be categorized as AE2/3 for example because they are occasionally not round and may belong to different denominations depending on how they are measured.
Table 4: AE Coin Sizes
| Denomination | Size |
| AE1 | more than 25 mm |
| AE2 | 21 – 25 mm |
| AE3 | 17 – 21 mm |
| AE4 | less than 17 mm |
The difference between a follis and an AE coin denomination is obscure.
The relationship between the denominations was historically altered by Constantine I in 318 AD, and the strandard was altering throughout this time.
So, unlike the denarius, Antoninianus, or follis, bronze coins no longer have a connection to precious metals.
The AE scale will therefore be used on coins starting with Constantius II and Constans.