When coin buyers look at different coins from around the world, they are looking for very specific coins. Take French coins, for example. Gold and silver francs from the Middle Ages are more valuable than, say, a solid gold commemorative coin issued by the French government for Bastille Day. Still, if a commemorative coin is unique and sought-after, a coin buyer might take interest. Here are some other French coins that coin buyers want, which may be in your great-grandmother's drawstring purse and brought over with the last major French emigration.
Napoleon III's Fifty Francs
Obviously, if you could carry fifty francs around France in the 1860's, you were wealthy indeed. These large denomination coins depicted the head of Napoleon Bonaparte III, the ruler of France at that time. His head is wreathed in laurels, so make sure your coin has these images and details before you attempt to sell it to a buyer.
Zinc and Aluminum Centimes from WWII
Just like the U.S. in WWII, the French used other metals to mint coins. While the U.S. used zinc-coated steel to mint pennies instead of copper during this time, the French opted for zinc and aluminum centimes. Different denomination coins used either the zinc or the aluminum. The coins should be stamped with a date between 1941 and 1945.
Pre-WWI Gold Coins
Gold coins went out of circulation in France right before the first World War. If you find a solid gold or gold-plated French coin, first make sure that it is dated prior to 1913. Then make sure it is really gold, and not painted gold or made of yellow brass, which when polished and shined looks gold.
Rare Modern Coin
The copper-coated steel 2 cent Euro, minted in France only has around 9,000 coins in circulation. If you find one in mint or near mint condition, you should add it to your collection. For whatever reason, this was an experimental coin minted for only one year. It has an imaginary female face on the "heads" side, purportedly to represent "Marianne," a femme de liberte, or "free woman." The back shows the typical Euro logo of the E.U. It is also valuable because some of the nations that joined the E.U. that year have since left it, making the number of stars on the back of the coin no longer valid in terms of representing the number of nations in the E.U.