What a gorgeous coin, Matthew. You have the larger of the two with this pattern, as follows:

40 francs: 27 mm diameter, 0.373 troy ounces gold
20 francs: 21 mm diameter, 0.187 troy ounces gold

To calculate an approximate catalog value for your coin, start with the melt value. This is the value of the puddle of gold you would get if you took a blow torch to your coin. (Hey, don't do it!) The melt value is equal to the current price of gold multiplied by the number of troy ounces. For instance, Kitco.com says the current price of gold is $1200 US dollars per troy ounce. So the melt value of your 40 franc coin would be 1200 x 0.373 = $447 US dollars. For a 20 franc coin it would be 1200 x 0.187 = $224. Be sure to use the current price of gold when you do the melt calculation.

Remember when dealing with precious metal, the word 'troy' is understood. 'Troy ounces' and 'ounces' are the same thing.

Here's where it gets tricky. This is an old, attractive, relatively scarce gold coin. So there is additional collector value added to the melt value. If the coin were damaged, heavily worn, scratched, stained, bent, or cleaned, the collector value is zero and the coin is worth melt value. At the other end of the scale, if the coin were fully uncirculated, fully lustrous, with plenty of great eye appeal and essentially no tic marks or scratches, and if it were encapsulated in a numismatic holder to guarantee authenticity, the collector value could be $1000 or more. Do you get the picture?

Here is a list of collector values for 20 and 40 franc coins of this era. Add these collector values to the melt value to get catalog value. Use our Important Terminology page to convert catalog values to actual buy and sell values. (Whew, this is complicated!)

20 FRANCS
heavily worn or damaged: $0 collector value
worn: $100 collector value
average circulated: $200
fully, absolutely uncirculated: $600
coin dated 1815B: $1000 in average circulated
coin dated 1822H: $1200 in average circulated
coin dated 1824MA: $1800 in average circulated

40 FRANCS
heavily worn or damaged: $0 collector value
worn: $200 collector value
average circulated: $400
fully, absolutely uncirculated: $800
coin dated 1816B: $1500 in average circulated
coin dated 1816L: $800 in average circulated
coin dated 1822H: $1500 in average circulated

Finally, use our Important Terminology page (link at upper left) to find out about catalog value.