How Much Does It Take From The Value

Nickel has a density of 8.908 g/cm3. I suppose your results are within range, seeing as how you may not have the proper equipment to accurately measure the volume of the metal.

The only thing you could do, if you're wanting to sell it, is to attempt to sell it. The worst that will occur is no one will bid/buy it. ebay is an option, a European coin auction is another. Not sure on requirements for one of the latter, but ebay is easy...but you might not get the attention of people who collect that series of 5 francs. Most auctions have a minimum bid requirement, and if you put a minimum requirement of 3000-4000 USD (which is the value of the coin if real), you just may get it. Some auctions allow you to add a description to the listing, which is where key things like weight, diameter, thickness, if it's magnetic, density, etc., will be of benefit (since if someone is skeptical about it being real, they will have measurements on which to compare to books and online numismatic resources, and base their final decision objectivity, rather than subjectively and automatically assuming such a rarity, ungraded, must be a counterfeit)


Plus...a Chinese counterfeit for quick comparison: (20140630) Not Allowed - Auto-Removed /item/1939-France-5-Francs-nickel-Coin-COPY/755393036.html EDIT: Just google that part of the link
Looks like two little dots, 1 off the nose, 1 off the chin; the back of the head looks like a weak strike, there are two dots below the neck near the A in the name by the rim, and 1 dot below the neck in the other direction; on the reverse you see some of the larger dots (berries?) that appear to touch the leaves and are very fat, not to mention the font looks off. Not to mention on the reverse, on the rim before the denticles begin left of the RF, there is a noticeable circular indentation in the coin, which is common of Chinese counterfeits (where they add the rim after the coin is struck, rather than at the same time like the originals), unfortunately since your coin's rim has a major ding right there, one cannot compare the two in that regard.

What I can say for certain, is that your coin is NOT of the same die pair that created that Chinese counterfeit. Is it the only die pair used for Chinese counterfeits? Maybe...maybe not.

Comparing your coin to http://img.ma-shops.com/chris/pic/combined770.jpg looks promising. And, if the above wasn't clear, you coin lacks the odd dots and larger berries.

This is an interesting problem, alexandra55. You are pursuing your research intelligently, there is expert help here to assist, yet there is still consensus that this extremely rare issue is possibly real. If your intent is to liquidate the coin, you could likely negotiate a consignment with a reputable house such as Spink's in London, and they would handle authentication and presentation themselves.

If your wish is to hold the coin, at least you can afford to be patient in your search for the facts. One thing you may do is look to the largest precious metals dealers within your reach, to see if any of them have an X-ray Fluorescence tester. This is an instrument which determines the exact alloy composition of a metal, and can conclusively prove that your coin is the correct alloy. This is an expensive tool ($US10,000+), so only the largest businesses have them.

The relevance of the test might depend partly on the accuracy of the original alloy. Were there trace levels of other metals, not necessarily part of the original specification, or is it metallurgically perfect and easily duplicatable? I could envision the possible need to enlist the owner of another example for the same test. And, as you mention, the results might not be conclusive.

Grasping at straws here. However, the Internet is large and there is information out there we haven't found yet.

opinions?