How to Identify an Old Coin: Six Clues on Every Coin

An old coin with a language you can’t read, a date that looks impossible, or no date at all can feel like a dead end. It isn’t. Almost every coin carries the same handful of clues — who issued it, when, what it was worth and where it was struck — and once you know where to look, you can usually pin it to a country, a ruler and a catalogue number in a few minutes.

1. Read the legend: who issued it

The legend — the lettering around the edge — usually names the country or ruler. Latin legends are common on European coins: HELVETIA is Switzerland, BRITANNIARUM or BRITT points to Britain, D·G· stands for Dei Gratia (“by the grace of God”) before a monarch’s name, and CONFOEDERATIO HELVETICA is Switzerland again. If the script isn’t Latin, identify the script first — Arabic, Cyrillic, Greek, Devanagari, Chinese — which immediately narrows the region.

2. Find the date — and its calendar

Not every date is in the Gregorian calendar, and many “impossible” dates are simply another system:

• Islamic (Hijri, AH) dates — used on Ottoman, Persian, Arab and other coins. A rough conversion is CE ≈ AH × 0.97 + 622, so AH 1293 is about 1876.
• Thai Buddhist Era (BE) — subtract 543 from the year.
• Japanese era years — a year number within an emperor’s reign, such as Meiji or Shōwa.
• Accession-year dates — some Ottoman coins show the sultan’s accession year plus a small regnal-year number.
• No date at all — normal for ancient coins and Chinese cash coins, which are identified by inscription and ruler.

3. Denomination and design

The denomination (penny, kreuzer, para, sen, centimes) is a strong regional clue even when you can’t read anything else. Portraits of rulers, coats of arms and national symbols — an eagle, a lion, a chrysanthemum, a tughra (the Ottoman sultan’s calligraphic signature) — narrow it further.

4. Look for a mint mark

A small letter or symbol shows where the coin was struck. On US coins it’s a letter such as P, D, S, O or CC; French coins use letters such as A for Paris; German coins use A–J for different mints. Mint marks matter because the same coin can be common from one mint and scarce from another.

5. Check the metal and weight

A kitchen scale that reads to 0.01 g and a magnet tell you a lot. Gold, silver, copper, brass and bronze are not magnetic; steel and nickel coins often are. Silver tends to tone grey, blue or gold; copper goes brown or green. Compare the weight and diameter with the catalogue specification — a wrong weight is one of the clearest signs of a fake or a plated coin.

Struck coins have sharp details and a crisp edge. Cast fakes often show soft, grainy surfaces, tiny bubbles, and sometimes a seam line around the edge where the mould halves met.

6. Match it in a catalogue

Once you have country, ruler or period, denomination and date, look it up. The Standard Catalog of World Coins (the “Krause” catalogue) is the long-standing reference and gives each type a KM number. Free online databases such as Numista cover hundreds of thousands of coin types with photos, and grading services publish detailed references for the coins they see most.

Legend

Country or ruler — identify the script first

Date

Check the calendar: Gregorian, AH, BE, era year

Denomination

Strong regional clue

Mint mark

Where it was struck; affects rarity

Metal and weight

Magnet + 0.01 g scale vs catalogue

Reference

Krause (KM) catalogue, Numista, grading-service guides

Ancient coins

Greek, Roman and Byzantine coins are identified by the ruler’s portrait and legend (often abbreviated — IMP CAES for “Imperator Caesar”), the reverse design, and sometimes a mint mark in the exergue at the bottom of the reverse. Genuine worn Roman bronzes are surprisingly common and affordable; silver and gold issues, and coins of rare rulers, are where forgeries concentrate, so buy those only from established dealers with a guarantee.

What not to do

• Don’t clean it. Cleaning destroys collector value, even on ancient coins.
• Don’t scratch or file the edge to “test” the metal.
• Don’t rely on one clue. A matching date with the wrong weight is still wrong.

The takeaway

Read the legend, decode the date in the right calendar, note the denomination and mint mark, weigh it and test it with a magnet, then confirm the match in a catalogue. Those six steps identify the great majority of old coins — and tell you when one is unusual enough to show a specialist.

At a glance

Decoding non-Gregorian coin dates

Calendar	Found on	Convert
Islamic (Hijri, AH)	Ottoman, Persian, Arab, Indian princely coins	CE ≈ AH × 0.97 + 622
Thai Buddhist Era (BE)	Thailand	CE = BE − 543
Japanese era year	Japan (Meiji, Taishō, Shōwa…)	Era start year + year − 1
Regnal / accession year	Some Ottoman and other coins	Accession year + regnal year
No date	Ancient coins, Chinese cash coins	Identify by ruler and inscription

Frequently asked questions

How can I identify a coin with no date?

Use the ruler’s name or portrait, the inscription and the design. Ancient Greek and Roman coins and Chinese cash coins are normally undated and catalogued by ruler and type.

What does D.G. mean on a coin?

“Dei Gratia”, Latin for “by the grace of God”, placed before a monarch’s name and title.

How do I tell if an old coin is silver?

Silver isn’t magnetic, tones grey to blue or gold, and should match the catalogue weight. A precise scale and a magnet screen out most plated or base-metal coins; a dealer can confirm with XRF.

How do I spot a fake old coin?

Check weight and diameter against the catalogue, look for soft or grainy details, casting bubbles and edge seams, and be cautious with rare silver and gold types from unknown sellers.

Sources and further reading

1. Numismatics — Wikipedia
2. Mint mark — Wikipedia
3. American Numismatic Association — American Numismatic Association

Links checked September 14, 2026.