How to Identify Roman Coins: A Step-by-Step Guide

What Roman Coin Identification Involves

A Roman coin is a document. It records the name and titles of the emperor who authorised it, the denomination and metal standard in effect at the time of striking, the reverse message chosen for that issue, and — from the late 3rd century onward — the mint and workshop that produced it. Learning to read these elements is the core skill of Roman numismatics, and it follows the same method whether you are examining a gold aureus of Augustus or a bronze nummus of Theodosius I.

Pliny the Elder, writing in the 1st century AD, noted that Rome first struck silver coinage in 269 BC and gold in 217 BC, during the Second Punic War.⁴ By the height of the empire, the Roman monetary system produced coins at dozens of mints across three continents, from Londinium to Alexandria. The sheer volume means that Roman coins survive in large numbers — they are the most commonly encountered ancient coins in the market — and the identification infrastructure built around them is the most developed in all of ancient numismatics.

The standard reference is RIC (Roman Imperial Coinage), a multi-volume series covering the full imperial period from Augustus to the fall of the Western Empire.¹ Online, OCRE (Online Coins of the Roman Empire) at numismatics.org provides free searchable access to RIC data. The NumisLens catalog covers 12,000+ Roman imperial types and is searchable by denomination, metal, ruler, reverse type, and legend text from the identification page or the Visual Wizard.

What follows is the six-step method that experienced numismatists apply, broken down so that a collector handling a Roman coin for the first time can follow it to a catalog attribution.

Step 1: Examine the Portrait

The obverse portrait is the single fastest way to narrow the identification of a Roman imperial coin. Roman emperors placed their own likeness on the coinage as a matter of policy from Augustus onward, and the portrait style changed in recognisable ways across the imperial period. Before you read a single letter of the inscription, the portrait tells you the approximate century and often the specific ruler. The crown or headdress worn by the emperor is the most immediately diagnostic feature, because different crown types correspond to specific denominations and specific periods in Roman monetary history.

Four portrait types account for the vast majority of Roman imperial coins:

Laureate — a wreath of laurel leaves tied at the back of the head. This is the standard obverse portrait for denarii, sestertii, and asses from Augustus through the mid-3rd century. An emperor wearing a laurel wreath on a silver coin of standard weight (approximately 3.0–3.9g, depending on period) almost certainly indicates a denarius. The laureate portrait is common across the full span of the Principate: from Augustus (27 BC) to the final denarii under Gordian III (c. 240 AD).

Radiate — a crown of radiating spikes projecting from the head, resembling sun rays. After Caracalla introduced the antoninianus around 215 AD, the radiate crown became the signal for a double-value denomination.⁶ A radiate portrait on a silver or silvered coin from the mid-3rd century is an antoninianus, nominally worth two denarii. On earlier coins — 1st and 2nd century — the radiate crown appears on the dupondius (a base-metal denomination worth two asses) to distinguish it from the visually similar as, which shows a laureate head. Confusing the radiate crown with a laurel wreath is one of the most common beginner errors in Roman coin identification.

Helmeted — the emperor wears a military helmet, sometimes with a crest or plume. Helmeted portraits appear intermittently on coins of military emperors and on certain commemorative issues. They are less common than laureate or radiate types but distinctive when present. On coins of Constantine I, a helmeted bust appears on issues from the period of the civil wars (c. 306–324 AD) and signals a specific phase of the reign.

Diademed — a jewelled band or pearl diadem tied at the back of the head. The diadem replaced the laurel wreath as the standard imperial headdress from the reign of Constantine I onward (c. 324 AD and after). If a Roman coin shows a diademed portrait, it dates to the late 3rd century at the earliest and most likely to the 4th or 5th century. The diadem is a strong period indicator: it immediately separates late Roman from early imperial coinage.

Beyond the crown type, note the direction the bust faces (almost always right in Roman coinage, with rare left-facing exceptions that carry attribution significance), and whether the portrait shows a bare head. Bare-head portraits appear on coins of Augustus (earlier issues before the laurel wreath became standard) and on certain bronze denominations where the bare head distinguishes one denomination from another.

Step 2: Read the Legend

Roman coin legends are abbreviated Latin, and they follow patterns that become readable with practice. The obverse inscription typically runs clockwise around the portrait, starting from the bottom-left. It contains the emperor’s name and a sequence of titles that serve as both identification and dating tools. Once you learn to parse these abbreviations, the legend alone can tell you who issued the coin, approximately when, and in what official capacity. The abbreviation system was consistent across centuries of Roman minting, which means the same set of title elements appears from Augustus through the late empire.

The most common abbreviations, with their full Latin forms:

Abbreviation	Full form	Meaning
IMP	Imperator	Military commander; used as praenomen from Augustus onward
CAES / CAESAR	Caesar	Imperial family name; later a title for the heir or junior emperor
AVG	Augustus	Title of the reigning emperor; conferred by the Senate
P M	Pontifex Maximus	Chief priest of the Roman state religion
TR P	Tribunicia Potestas	Tribunician power; renewed annually and used for dating
COS	Consul	Followed by a numeral (II, III, IV, etc.) indicating consulship count
P P	Pater Patriae	Father of the Fatherland; an honorific title
P F	Pius Felix	Dutiful and Fortunate; standard from the late 2nd century (Severan dynasty) onward
D N	Dominus Noster	Our Lord; appears from the early 4th century and standard from Constantine I onward
S C	Senatus Consulto	By decree of the Senate; appears on base-metal denominations (sestertii, dupondii, asses) throughout the Principate

A worked example: the legend IMP CAES NERVA TRAIAN AVG GERM P M reads as “Imperator Caesar Nerva Traianus Augustus Germanicus, Pontifex Maximus.” The name identifies Trajan. The title Germanicus was associated with his command on the Rhine frontier. Pontifex Maximus dates the coin to after his accession in 98 AD. If the legend continues with TR P COS II, the tribunician power and second consulship narrow the date to 98–99 AD.¹

A second example from the late empire: D N CONSTANTINVS P F AVG reads as “Dominus Noster Constantinus Pius Felix Augustus” — “Our Lord Constantine, Dutiful and Fortunate, Augustus.” The use of D N rather than IMP immediately signals a late Roman coin (post-284 AD). The P F was standard by this period.

The reverse legend names the type or commemorative message: VICTORIA AVG (Victory of the emperor), SALVS REIPVBLICAE (welfare of the state), GLORIA EXERCITVS (glory of the army), GENIVS POPVLI ROMANI (spirit of the Roman people). Read the reverse legend together with the imagery to identify the specific reverse type, which is one of the primary keys to looking up the coin in RIC.

Step 3: Identify the Denomination

Metal and weight together identify the denomination. Roman coins did not carry face values — the denomination was implicit in the combination of metal, size, and weight, and any ancient Roman handling a coin would have recognised the denomination by sight and feel. Modern collectors do the same thing with a scale. The Roman monetary system went through several major restructurings across five centuries, but at any given period, the active denominations followed fixed weight standards that are still measurable today. Howgego provides the fullest discussion of how denomination systems functioned in practice.⁷

Denomination	Metal	Weight	Period
Aureus	Gold	~8.0g (Augustus); ~7.3g (Nero onward)	1st c. BC – 4th c. AD
Solidus	Gold	~4.5g (1/72 Roman pound)	309 AD onward (Constantine I)
Denarius	Silver	~3.8g (Augustus); declining to ~3.0g (Severan)	211 BC – mid-3rd c. AD
Antoninianus	Silver/billon	~5.0g initially; ~3.5g debased	c. 215 – 294 AD
Siliqua	Silver	~2.2g (1/144 Roman pound)	4th – 5th c. AD
Sestertius	Brass (orichalcum)	~25g	1st c. BC – mid-3rd c. AD
Dupondius	Brass (orichalcum)	~13g	1st c. BC – 3rd c. AD
As	Copper	~10g	3rd c. BC – 3rd c. AD
Follis	Bronze (silvered)	~10g initially; reduced over time	294 – mid-4th c. AD (Diocletianic reform)
Nummus (AE3/AE4)	Bronze	~2–5g	Mid-4th – 5th c. AD

The denomination system changed in three major phases. From Augustus to the mid-3rd century, the system built around the gold aureus, silver denarius, brass sestertius and dupondius, and copper as functioned with remarkable stability. The denarius lost silver content gradually — from nearly 98% under Augustus to around 50% under Septimius Severus — but the system held.⁶ Around 215 AD, Caracalla introduced the antoninianus at roughly 1.5 times the denarius weight, and the coinage entered a decades-long debasement that collapsed the silver content to under 5% by the 260s.

Diocletian’s reform of c. 294 AD rebuilt the system around the gold aureus (later replaced by Constantine’s solidus at ~4.5g), the silver argenteus, and the large bronze follis.¹ The follis itself was then progressively reduced across the 4th century, producing the smaller bronze denominations that collectors refer to by flan size: AE2 (21–25mm), AE3 (17–21mm), AE4 (under 17mm). These size designations are informal conventions rather than ancient denomination names, but they are standard in dealer descriptions and auction catalogs.

Step 4: Check the Reverse Type

The reverse of a Roman coin carries a deliberate message chosen for that issue, and it is one of the primary keys to attribution. Roman reverse types fall into recognisable categories that recur across many reigns, but the specific combination of ruler and reverse narrows the identification to a small number of possible RIC entries. Burnett provides the clearest overview of how reverse types functioned as political communication.⁶ The reverse legend and the imagery should be read together: the legend names the type, and the imagery depicts it.

Deities and personifications are the largest category. Jupiter (IOVI CONSERVATORI, “To Jupiter the Preserver”) appears on coins from Augustus through the Tetrarchy. Mars (MARTI VLTOR, “To Mars the Avenger”) signals military themes. Sol Invictus — the Unconquered Sun — dominates reverse types under Aurelian and the early Tetrarchy (SOLI INVICTO COMITI, “To the Unconquered Sun, companion [of the emperor]”). Personified virtues — Victoria, Concordia, Pax, Salus, Securitas — appear as standing or seated female figures with distinctive attributes: Victoria holds a wreath and palm, Pax holds an olive branch, Salus feeds a serpent from a patera.

Military types show legionary standards, soldiers, trophies, or captives. GLORIA EXERCITVS (“glory of the army”) on Constantinian bronzes shows two soldiers flanking one or two military standards — the reduction from two standards to one helps date the issue. FEL TEMP REPARATIO (“restoration of happy times”) under Constantius II shows a soldier spearing a fallen horseman. These military reverses are among the most commonly encountered types in the market.

Architectural types depict temples, triumphal arches, harbour structures, or the Colosseum. The sestertius of Titus showing the Colosseum (RIC II 184) is one of the most famous Roman coins in existence, though genuine examples are rare and expensive. More accessible architectural types include the camp-gate reverse (PROVIDENTIAE AVGG) common on Constantinian bronzes, which shows a stylised Roman military camp entrance with turrets.

Commemorative and dynastic types mark specific events: conquests, anniversaries, the designation of an heir. The SIGNIS RECEPTIS type of Augustus commemorates the diplomatic recovery of the legionary standards lost to Parthia at Carrhae in 53 BC. Consecratio types — showing an eagle or a funeral pyre — were struck after an emperor’s death to mark his deification.

How does the reverse help identification? Once you have the ruler from the obverse legend and the denomination from weight and metal, the reverse type and its legend narrow the match in RIC to a manageable number of entries — often fewer than ten. At that point, the mint mark (if present) or the portrait variant resolves the specific type.

Step 5: Read the Mint Mark

Mint marks on Roman coins identify the issuing mint and, in most cases, the specific workshop (officina) within that mint. They appear primarily from the Diocletianic reform of c. 294 AD onward, though some earlier coins — notably under Gallienus and the soldier-emperors — carry proto-mint-marks. For late Roman coinage, the mint mark is the single most precise attribution tool available. Without it, many 4th-century bronze types are nearly identical across a dozen mints; with it, attribution is exact.

Mint marks are found in the exergue — the lower section of the reverse, below a horizontal ground line that separates it from the main reverse type. Some marks also appear in the reverse field (the open area beside the main figure), particularly on 3rd-century coins. The format typically combines the mint abbreviation with an officina indicator:

Mint mark	Mint	Notes
PTR / SMTR	Trier (Treveri)	One of the most prolific western mints under Constantine I
SMANT	Antioch	SM = Sacra Moneta; followed by officina letter (A, B, Γ, etc.)
SMAN	Antioch (variant)	Shorter form of the Antioch mint mark
CON / CONS	Constantinople	Active from c. 326 AD; major mint of the eastern empire
AQ / SMAQ	Aquileia	Northeast Italy; important mint for Italian and Danubian distribution
SIS / SMSIS	Siscia	Modern Sisak, Croatia; one of the largest Balkan mints
LON / PLN	Londinium	London; operated intermittently, mostly under the Tetrarchy and Constantine I
R (in wreath or field)	Rome	Early marks; later RM or SMR
ALE / SMAL	Alexandria	Primary mint for Roman Egypt; struck both imperial and local types
HER / SMHE	Heraclea	Thrace; important Balkan mint in the 4th century

The officina letter or numeral follows the mint abbreviation: SMANTB means Antioch, second officina; PTRΓ means Trier, third officina (using the Greek numeral gamma). Roman mints typically operated two to seven officinae simultaneously, each producing coins from its own dies. The officina letter does not affect the coin’s identification for most purposes but is recorded in RIC and matters for die-study research.

For coins struck before the Diocletianic reform — the entire Principate from Augustus through Carinus — mint attribution relies on die style, weight standard, and hoard evidence rather than explicit mint marks. Sutherland and Carson discuss these attribution methods at length in the relevant RIC volumes.¹ Precious-metal coins of the early empire were struck at a small number of workshops (primarily Rome and Lugdunum for gold and silver), which limits the attribution problem. Base-metal coins from this period are more challenging because multiple mints could produce similar types without distinctive marks.

Step 6: Cross-Reference With Catalogs

With the ruler, denomination, reverse type, and mint established from Steps 1–5, the final step is to match the coin against a published catalog. The catalog confirms the attribution and provides a standard reference number that dealers, auction houses, and collectors use to describe the coin precisely. A coin described as RIC VII Trier 435 communicates all essential identification details in four words: the catalog (RIC volume VII, covering the period 313–337 AD), the mint (Trier), and the specific type number. This shorthand is the lingua franca of Roman numismatics.

RIC — Roman Imperial Coinage, edited by Sutherland, Mattingly, Carson, and others across ten volumes covering Augustus to Valentinian III.¹ This is the standard reference. Each volume is organised by emperor, then by mint, then by denomination. The quality varies across volumes — some (particularly the early Mattingly volumes) reflect scholarship from the 1920s and 1930s that has been partially superseded. Volume I was revised by Sutherland in 1984 (RIC I²). Volume VII (Bruun, 1966) covering Constantine I remains the standard for Constantinian coinage.

BMC — Mattingly’s Coins of the Roman Empire in the British Museum, published in six volumes from 1923 to 1962.² BMC provides more detailed physical descriptions than RIC and includes die comparisons, but covers only the coins held by the British Museum. It is most useful as a supplement to RIC rather than a standalone reference.

Sear — David Sear’s Roman Coins and Their Values, now in five volumes for the full imperial period.³ Sear cross-references to RIC and provides approximate market values, making it a practical collector’s handbook. The Sear number (S- prefix) is widely used in dealer catalogs and on VCoins and MA-Shops listings.

OCRE — the Online Coins of the Roman Empire database at numismatics.org is the free digital equivalent of RIC. It provides a searchable interface to RIC data with photographs from institutional collections. For most identification work, OCRE is the fastest route: enter the emperor name and any combination of denomination, reverse type, and mint, and it returns matching RIC entries with images.

For Republican coinage (pre-Augustus), the standard reference is Crawford’s Roman Republican Coinage (1974), cited as RRC or Crawford.⁵ Republican coins lack emperor portraits — they show deity heads, symbols, and moneyer designs — and require a different identification approach, built around the moneyer’s name and the reverse type rather than an imperial portrait.

Common Identification Mistakes

Roman coin identification has a handful of recurring errors that catch both new and intermediate collectors. Most stem from assumptions that seem reasonable but do not hold across the full range of Roman coinage. Knowing these pitfalls in advance saves hours of misattribution and prevents costly purchasing errors when the coin in question turns out to be something other than what the seller described.

Confusing the radiate crown with the laurel wreath

This is the single most common beginner error. The radiate crown — spiky rays projecting from the head — looks superficially similar to the laurel wreath on worn coins. But they signify entirely different things. On a 1st- or 2nd-century coin, the radiate crown indicates a dupondius (worth two asses), while the laureate head indicates an as. On a 3rd-century coin, the radiate crown identifies the antoninianus, not the denarius. Getting this wrong leads to misidentifying the denomination, which cascades through the entire attribution. Look for distinct triangular spikes projecting outward: that is radiate, not laureate.

Misreading legends on worn coins

Worn coins lose detail from the high points first, which in Roman coins means the tops of the letters and the fine features of the portrait. A partially legible legend can mislead: CONSTANTINVS and CONSTANTIVS differ by one letter, but they identify different emperors. Similarly, MAXIMIANVS could refer to Maximian (Herculius), Galerius (Maximianus), or Maximinus II (Daia). When the legend is unclear, use the portrait style and reverse type as cross-checks rather than guessing at individual letters.

Assuming all bronze coins are worthless

Bronze coins from the late Roman period — 4th and 5th century nummi — are genuinely inexpensive, often $5–20 in average condition. But earlier Roman bronzes can be worth far more. A sestertius of Nero in VF with the Harbour of Ostia reverse (RIC I 178) sells for $5,000–15,000 at major auction houses. Sestertii of Hadrian, Marcus Aurelius, and Trajan in high grade regularly bring $1,000–5,000. The metal alone does not determine value.

Ignoring the reverse

Collectors sometimes focus exclusively on the portrait and legend while treating the reverse as decoration. This is a mistake. The reverse type is often the decisive factor in attribution. Two coins of Trajan with identical obverse legends but different reverses may have different RIC numbers, different mint attributions, and different market values. The reverse legend is as important as the obverse legend for catalog lookup.

What to Do After Identification

Once you have identified the ruler, denomination, reverse type, and — where applicable — the mint, you have the information needed to assign a catalog reference number. That number is the coin’s permanent identifier in the numismatic literature, and it should accompany the coin in any collection record, insurance listing, or sale description.

The NumisLens identification tool provides AI-assisted coin identification that follows the same six-step method described in this guide. Upload an image or search by the details you have gathered — ruler, denomination, reverse type, mint — and the system matches against the full catalog of 12,000+ Roman imperial types.

For deeper research into specific rulers, the NumisLens reference guides cover individual reigns in detail:

• Augustus Coins: A Historical Reference — 800+ types across 14 mints, from gold aurei to bronze asses
• Constantine I Coins: A Collector’s Reference — 4,000+ types across 17 mints, the most prolific coinage of late antiquity
• Ancient Greek Coin Identification — for coins that predate the Roman imperial period

The full NumisLens type catalog covers Roman, Greek, and Hellenistic coinage. The emperor index provides a browsable list of all rulers in the database with links to their cataloged types.

Frequently Asked Questions

References

1. Sutherland, C.H.V. & Carson, R.A.G. (eds). The Roman Imperial Coinage (RIC). 10 vols. London: Spink, 1923–1994.
2. Mattingly, H. et al. Coins of the Roman Empire in the British Museum (BMC). 6 vols. London: British Museum, 1923–1962.
3. Sear, D.R. Roman Coins and Their Values. 5th rev. ed. (5 vols, Republic to fall of the Western Empire). London: Spink, 2000–2014.
4. Pliny the Elder, Naturalis Historia, XXXIII.42–47. Trans. Rackham, H. (1952). Loeb Classical Library, Harvard University Press.
5. Crawford, M.H. (1974). Roman Republican Coinage. 2 vols. Cambridge University Press.
6. Burnett, A. (1987). Coinage in the Roman World. London: Seaby.
7. Howgego, C. (1995). Ancient History from Coins. London: Routledge.
8. Bland, R. & Loriot, X. (2010). Roman and Late Roman Gold and Silver Coins Found in Britain. Royal Numismatic Society Special Publication 46.