The 20-franc standard: Marengo, Napoléon and Vreneli
The Italian 20 lire, the French 20 francs and the Swiss 20 francs are the same coin struck in three countries: 6.4516 grams of gold at 900 thousandths, which is 5.8064 grams of fine gold, on a disc 21 mm across. That is why the three trade together and why their prices are worth reading side by side.
| coin | fine gold | purity | struck | typical price |
|---|---|---|---|---|
| Marengo 20 Lire | 5.81 g | 900 ‰ · 21.6 kt | Italy · 1861–1897 | — |
| Napoléon 20 Fr | 5.81 g | 900 ‰ · 21.6 kt | France · 1803–1914 | — |
| Vreneli 20 Fr | 5.81 g | 900 ‰ · 21.6 kt | Switzerland · 1897–1949 | — |
The standard is older than the union that made it common. France fixed it in 1803; in 1865 the Latin Monetary Union — France, Italy, Belgium, Switzerland, later others — agreed that a franc, a lira and a Swiss franc would be the same weight of metal, so that the coins of one country would spend in another. The gold pieces of that agreement are still the small change of the European bullion market a century after the agreement ended.
Italy struck its 20 lire from 1861 to 1897 and the market calls it the marengo — a name it borrowed from an earlier, different coin, which is worth knowing before buying one from a photograph. France struck the 20 francs from Bonaparte to 1914, in enough quantity that it is the most widely held of the three. Switzerland struck the Vreneli from 1897 to 1949, and most of them never circulated, so they usually turn up in better condition.
Because the gold is identical, the price difference between them is entirely premium — and it is not small. A coin this size carries more workmanship per gram than an ounce does, so its premium over spot is structurally higher; on top of that sits whatever each shop asks for the particular one it has.
For a buyer that is the whole point of putting them on one page: three coins, one gold content, and a spread you can see.