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1814 Napoleon Bonaparte 20 Francs - Genuine?

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25 Posts
 Posted 03/24/2023  10:13 pm Show Profile   Bookmark this topic Add ClusterCoin to your friends list Get a Link to this Message

I would like an opinion on whether this 20 Franc coin is genuine. Estate auction.


It weighs 6.43g (correct), has the correct diameter, but my Sigma Metalytics machine fails the coin on its 90% gold/balance Cu setting. The measured resistance is 12.18, with the small wand. 91.6% gold coins usually have a value of 8.8, so this 20 Franc coin is wildly off the mark.

Are Napoleon coins alloyed with copper, silver, or are impurities causing the reading?

The coin itself looks good with lustre on the reverse.
Edited by ClusterCoin
03/24/2023 11:39 pm
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20945 Posts
 Posted 03/25/2023  08:19 am  Show Profile   Bookmark this reply Add sel_69l to your friends list Get a Link to this Reply
Time of the Napoleonic Wars.
The British Royal Mint 'forged?' the 1815 Louis XV111 20 Francs in the correct gold alloy, with an 'R' mint mark after the date, for payment of supplies for the Duke of Wellington's army.

It is worth consideration that the coin pictured here may also be forged?, also in the correct gold alloy.

As a collector, I wouldn't worry too much about that; I would probably collect it anyway, due to it's historical significance.

Would be worthwhile to do an XRF test.
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25 Posts
 Posted 03/25/2023  08:37 am  Show Profile   Bookmark this reply Add ClusterCoin to your friends list Get a Link to this Reply
Thank you sel_69l for your response.

I have mixed feelings about this coin. It's the last year of Napoleon's reign, so perhaps the mint wasn't as stringent in its coin production? Or as you say, it's possible this coin wasn't made in France.

The Sigma is a wonderful tool but obviously it's not foolproof. It is possible to get erroneous readings on embossed bullion or high relief coins, but this coin does not have those features. I wish I had my calipers with me to test the thickness.

As for an XRF test, I wish I could afford one. I don't have another coin of the era to compare it against. On the same day I did test an 1874 20 Franc Belgian coin and it tested perfect on the Sigma. Both coins are meant to be 90% gold, but the Napoleon coin was way off expected value.

I think someone will snap up the coin at auction on Monday anyway. I have been going to estate auctions for a few years and have never seen anyone test the authenticity of coins. In the past I have spotted some fake Australian 34/35 florins for auction, so I'm always wary of what's on offer.
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1792 Posts
 Posted 03/25/2023  4:52 pm  Show Profile   Bookmark this reply Add realeswatcher to your friends list Get a Link to this Reply
Color looks OK, edge looks good, a slight bit of the usual adjustment marks... I wouldn't have been suspicious about it.
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25 Posts
 Posted 03/27/2023  08:02 am  Show Profile   Bookmark this reply Add ClusterCoin to your friends list Get a Link to this Reply
The coin ended up selling for AU$550+16%, which is below reserve. That is AU$640, or US$429. As the coin contains US$364 of gold that is quite a low sale price.

90% gold coins attract 10% GST in Australia (999 gold does not), so the cheapest possible retail price for a genuine Napoleon coin would be US$400. I have seen generic 19th and 20th century 20 Franc French and Belgian coins sell for more.

I did not bid on the coin as I think it's suspicious. The high Sigma measurement reminded me of a fake Australian florin I have that's made of a lead alloy. I wouldn't be surprised if this 1814 coin is gold plated lead alloy.

Anyway, good luck to the buyer and I hope they didn't get ripped off.

Edited by ClusterCoin
03/27/2023 08:05 am
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