Ancient coins were made by hand-striking metal blanks between two engraved dies, a process that remained fundamentally the same for over a thousand years. From the earliest electrum coins of Lydia around 600 BCE through the Roman Empire, mints refined raw metal, cast it into small discs of precise weight, carved detailed designs into bronze or iron tools, and hammered those designs into each coin one at a time.
Refining the Metal
Coin production started with raw ore. By the late sixth century BCE, Greek metalworkers could smelt metals from ore, test the purity of the refined product, and separate alloys into their individual components. This wasn’t crude work. Analysis of surviving coins shows that both Greek and Roman mints achieved remarkably high levels of metal purity and could adjust the fineness to a target standard.
The most common coinage metals were gold, silver, electrum (a natural gold-silver alloy), and bronze. Silver was dominant for everyday high-value transactions, especially in the Greek world. The Athenian tetradrachm, one of the most widely circulated coins in antiquity, was struck in silver at a standard weight of about 17.2 grams. Rome’s silver denarius started as a nearly pure silver coin, though its purity famously declined during periods of financial stress, dropping from pure silver to under 95% fine, then to 90%, with some coins falling as low as 86% silver as the mint deliberately mixed in copper to stretch its silver supply.
Making the Blanks
Once the metal was refined, workers needed to turn it into small discs (called flans or blanks) of the correct weight. The most common method was open casting: pouring molten metal into molds to produce rough, round pieces. Getting the weight right mattered enormously. Greek city-states and later Rome maintained strict weight standards, because the value of a coin was tied directly to the metal it contained. The Athenian drachma, for example, was pegged at 4.3 grams of silver.
After casting, the blanks often needed cleaning. Heating metal in an open mold caused impurities to rise to the surface through oxidation. Workers removed these by washing the blanks in an organic acid solution or simply scraping the oxidized layer off by hand. The result was a clean, correctly weighted disc ready for striking.
Engraving the Dies
The artistic heart of coin production was die engraving. Each coin required two dies: one for the front (obverse, typically showing a deity or ruler) and one for the back (reverse, often depicting an animal, symbol, or scene). These dies were small cylindrical tools with the coin’s design carved into one flat end, in mirror image, so the struck coin would read correctly.
The preferred material for dies was bronze with a relatively high tin content, which made the metal harder and more durable. Iron dies were also used on occasion. Engravers worked with iron or steel burins and small chisels to cut metal away from the die face, punches to press shapes into the surface, and bow drills tipped with corundum or another abrasive to bore fine details. The best Greek engravers produced miniature works of art. Some dies from Syracuse and Athens rival anything produced in the Renaissance, with portraits showing individual strands of hair and realistic facial features, all carved into a surface smaller than a thumbnail.
Die engraving was slow, skilled work, and dies wore out. A single die might produce a few thousand coins before cracking or losing detail. Mints needed a steady supply of fresh dies to maintain production, which is why ancient coin collectors today can identify individual dies and use them to estimate how many coins a particular mint produced.
Striking the Coin
The striking process itself was straightforward but physically demanding. The lower die (usually the obverse) had a spike on its base that was driven into a wooden block or anvil to hold it steady. A worker placed a blank disc on top of this fixed die. The upper die was then held over the blank by hand, and a second worker struck it with a heavy hammer. The force of the blow pressed the blank metal into both die faces simultaneously, imprinting the designs on both sides of the coin in a single strike.
This sounds simple, but it required coordination. The blank had to be centered, the upper die had to be held straight, and the hammer blow had to land squarely. Misalignment produced off-center strikes, and a glancing blow could create double images. These errors are common on surviving ancient coins, a reminder that every single coin was made individually by hand. A skilled team could strike several hundred coins in a day, though estimates vary widely depending on the period and mint.
Hot Striking vs. Cold Striking
Whether the blank was heated before striking depended on the metal. Gold and silver are relatively soft and can be struck cold, though heating them made the process easier and reduced the risk of cracking. Bronze is harder and was more often struck hot. Some coins show evidence of being struck while still warm from casting, essentially going straight from the mold to the die before the metal fully cooled. Heating the blank also helped the metal flow into the fine details of the die, producing a sharper image.
Quality Control and Adjustments
Ancient mints took weight standards seriously. Coins that came out too heavy could be filed down, and many ancient coins show file marks around their edges where metal was removed to bring them to the correct weight. Coins that were too light were melted down and recast. This attention to weight was practical: merchants and money changers routinely weighed coins rather than simply counting them, so an underweight coin would be spotted immediately.
Purity was harder to verify, and this is where governments sometimes cheated. Rome’s deliberate debasement of the denarius in 90 BCE is a well-documented example. Facing a financial crisis, the mint began alloying silver with 5 to 10% copper, effectively stretching the silver supply while maintaining the coin’s face value. When the Roman official Gratidianus later published an edict addressing the problem, the mint sharply reversed course and restored the denarius to high-quality silver. This back-and-forth between honest coinage and debasement repeated throughout Roman history and is readable today in the chemical composition of surviving coins.
Scale of Production
Major mints were organized operations. Rome’s central mint on the Capitoline Hill employed teams of engravers, smelters, blank makers, and strikers working in parallel. Greek city-states operated smaller but similarly specialized workshops. The division of labor was clear: one group refined metal, another cast blanks, specialists engraved dies, and separate teams handled the physical striking.
Despite the hand-powered process, output could be impressive. Athens produced enormous quantities of tetradrachms to fund its navy and empire during the fifth century BCE, drawing on the silver mines at Laurion. Rome scaled production even further, operating multiple mints across the empire by the third century CE to keep up with military payrolls. Each mint followed the same basic process that had been established centuries earlier: refine, cast, engrave, strike. The tools improved incrementally, but the fundamental technique of hammering a blank between two dies persisted until mechanical screw presses finally replaced hand striking in the early modern period.