By starting to talk about coins in Western Europe—with Charlemagne’s penny—I passed over what was actually the dominant coin in the early medieval years. Constantinople controlled eastern Mediterranean trade all through the Middle Ages, and even when its military power was not enough to keep its eastern lands safe from Muslim conquest, its currency was still the stablest.
Constantinople was able to strike gold coins when Western Europe was dealing only in silver and copper. Its gold coin was called the solidus (which eventually corrupted to the English “shilling”) or nomismus. The port city managed a high volume of wholesale trade, so it needed coins to represent large values.
Roman coins had shown pictures of their emperors in profile, but the Byzantine style showed emperors looking straight out in full view. Although some old Roman coins circulated in Europe, Charlemagne and his descendants copied Byzantine coins, showing their faces too. Byzantine coins usually had a cross or saint on the reverse side, another detail copied by Western Europe.
By the 1200s, the coins circulating in the eastern Mediterranean would have been split between Byzantine solidii—the gold no longer pure—-and the Islamic dinar. Muslim power was still nominally centered in Baghdad, although its regions were operating independently and certainly minting their own coins. The earliest Umayyad dynasty coins featured an image of the Caliph, but later Muslim coins were covered entirely with script. Here is an article on some medieval Islamic coins, with a few pictures.
Gold came from Africa and the Far East, so the Muslim Sultanates always had much better access to it than Western Europe’s silver-based kingdoms. Their coins were pure and well made, since they also had better access to ancient metal-working skill, a trade still relatively new in the Germanic forests. Of course, they also issued silver coins of lesser value.
During the 1200s, some of the Italian merchant cities were able to trade profitably enough with Constantinople, Damascus and Cairo that they, too, had sufficient gold to mint their own coins. Venice was in some ways a miniature Constantinople; it profited very much by both trade and robbery from Byzantium, including importing its craftsmen. Late medieval Venice minted high quality silver and gold coins that soon became the standard for Western Europe.
Venice’s silver coin was called the grosso, produced during the Fourth Crusade and at that time the highest value coin in Europe. The grosso’s design included a circle of beads around its edge, so that shaved and clipped coins were easy to spot. Venice then created the gold ducat, but by then other merchant cities were striking gold coins too. Florence copied the design of the grosso, with an added lily, and called it the florin. The florin became the basis for all late medieval coins in Western Europe.
About a century after Florence minted its first gold coins, England’s Henry III created an English florin as part of his currency reform. The attempt was a failure, since the English florins used much less gold and were not popular at international fairs, compared to other coins. Withdrawn, melted, and restruck, the same gold became a new coin, the noble, which stayed in English circulation into Shakespeare’s time. The noble had only one problem: it was a stronger currency than France’s at that time, and merchants tended to trade it into French circulation, leaving England short of high-value coins. By the close of the Middle Ages, Western Europe’s coins were high quality, a far cry from their earliest clumsy silver pennies. Here is a late medieval English noble.
By the 1300s and 1400s, basic modern accounting had been developed. Banking started as a service for merchants within their own networks, in which a supply of coins was kept under guard at each city, allowing a merchant to travel light. Instead of carrying a locked casket, making himself a target for mountain robbers, he could deposit the sum in one city and travel with only a paper stating the sum so he could withdraw it in another. Coins were still highly important, but the basis of an accounting economy that wouldn’t require coins had been established.