Suspicious 1778 Charles III 8 Reales (Mexico City)

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Today I'm presenting a 1778 Charles III 8 Reales with "oM" mint mark and "F.F." assayer. What brings me here is the fact it weighs 26.2 grams and still retains all of its details. From what I understand, that is a little light and has me questioning the authenticity of the coin.

My last post regarding an 1808 8 Reales was determined to likely be a numismatic forgery based on the grounded down edge of the coin to conceal a seam. This coin has the correct pattern on the edge that is intact from what I can see, I have the photos below.

I have the details below if they'll help in deducing what I have here, I theorize this may be some silver cast counterfeit due to the specific gravity I recorded. If anybody can input whether this is somehow genuine or is some type of counterfeit it would be much appreciated, thank you and happy new year!

Details:
Weight is 26.26g
Diameter is 38.5mm
Width is 2.3mm
Specific Gravity ranged 10.28-10.31

This one has me a bit stumped. Something about it looks fishy, but I can't pick anything out as glaringly wrong

The edge shows an unusual surface quality to me, seems like it could be a result of casting but I am unsure.

Hope others have more ideas

Find a friend or a business that has access to a small neodymium magnet. That may require a bit of a 'phone around.
Perhaps an old loudspeaker magnet or a powerful electromagnet could be suitable for this test, but neodymiun can attract a far wider range of nominally non magnetic metals and alloys.

Compare the attractive strength of the coin in question against a genuine pillar dollar.
Be careful to make sure when doing this test, that you phone or expensive watch is well away.

Edited by sel_69l
01/01/2022 03:55 am

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There was no need to phone around, I have multiple neodymium magnets that I use to test my coins. I forgot to mention in my initial post that this coin is not magnetic, apologies for that. Same goes for my genuine real coins, I tested a 4 real and multiple 2 real coins. I did a dangle test where I hanged the 8 real coin in front of a neodymium magnet and there was no attraction whatsoever.

Neodymium magnets can have a response for some metals and alloys that are nominally non magnetic.

These sort of magnets open up the possibility for wider comparative magnetic testing also for coins that also are nominally non magnetic.

That would make it harder for those Chinese coin fakers !

Perhaps a CCF member can advise from where a small neodymium magnet can be purchased within the U.S.

Assuming your scale is accurate it cannot be genuine with that low weight. You do need a scale accurate to 3 decimal places to produce a specific gravity reading of two decimal places so I'm also assuming your SG is actually 10.2-10.3 which would indicate it is probably a bit lower than 90% silver.

You say you think it might be a cast counterfeit, but many near 90% silver counterfeits for trade with China were struck, according to the expert, swamperbob.

Edited by jgenn
01/01/2022 5:09 pm

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I used two scales that can do 2 decimal places and they were reporting 26.26 grams so I'm pretty certain that weight is correct. With regards to your statement about the SG, I must agree since my measurement is only a crude one and I don't have a scale that can do 3 decimal places on hand. I can assume if this is solid of whatever metal composition it is, it would likely be some more impure silver alloy resulting in the lower weight/density.

I understand in the past at some mint locations, they were purposefully lowering silver content. But I could not find anything for this year and mint location that this was being done, so I assumed it might be a "made for China" contemporary piece. Interestingly enough, assuming it is a made for China piece, then it appears like it never circulated much due to lack of wear and chopmarks.

With its low weight, it would not have circulated successfully as a Trade dollar.

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