1787 Bust 8 Reales - Authentic or Counterfeit

Hello all,

Curious to hear from the collective knowledge on the forum. I've done some research of my own on it but am not sure what to make of this one, as there seem to be many many factors to consider when determining authenticity of this particular type of coinage.

This particular coin weighs 26.8g. I believe I see two overlap marks exactly opposite each other on the edge design. Half of the edge has diagonal cut marks in it. There also looks like there might be some doubling on the date, and the left side windows on the castles don’t look perfectly rectangular under magnification. Any thoughts on this one?

 

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Hey , really nice coin. I wish I knew more for ya .Oh, looks good to me .Thanks for sharing .

 

It looks genuine to me, but cleaned with hairlines.

 

@johnmilton . I was thinking the same thing .

 

To be honest the coin looks ok to me. 26.8g is a little low but still within range especially for a worn coin. I do not see any doubling.

It does look cleaned but it's starting to gain patina back. As for the file marks, maybe they are adjustment marks? It looks like it was shaved off before the edge design was crimped. I'm sure someone here will know.

Nice old world coin!

 

Nice Date also .

 

Coin looks Ok to me too.

 

@GDJMSP question for you... can a coin get its patina back a long time after a cleaning that removed it?

 

Good question. I don't see why not .JMO

 

I know enough to know that I don't know the answer, but also that he can provide the technical explanation of it.

 

That would be nice. I would like to know also. Thanks

 

A cleaned coin can retune, but the hairlines from cleaning will remain. They might be harder to see, but an experienced grader will probably spot them. Sometimes such coins will get straight grades either because the grader missed them (People don’t realize how little time TPG personnel are expected to take grading coins.), or they become “market acceptable.”

 

It's normal for coins to re-tone back to market acceptability. The damage from cleaning still remains but the patina usually makes it hard to see. It's widely accepted in ancient and older US type coins that circulated (and usually AU/UNC) specimens have been cleaned at some point.

I've even had some of my cleaned coins re-tone in my possession. Here's a capped bust dime I received on my birthday in 2019. At the time it had very obvious and bright cleaning, one year later of sitting in my coin cabinet and the occasional campout and it's gained a black circcam patina.



I apologize if this is sort of off track from the OP.

 

This is the major visible anomaly. Diagonal cut marks are not likely to be a result of the stamping of the blank from the fillet. Adjustment for excess weight was typically done by filing across the surface of the blank. I suppose a blank with metal spurs from a poor stamp might get filed along the edge, but it would have to be a severe enough case to interfere with the upsetting and edging -- a process that would normally crush out any edge issues with the pressure from the edging mill.

The big problem with 8 reales of this time period is that they were counterfeited by operations that used similar, but often not identical, manufacturing techniques. These are hard to spot but they generally cheated on the silver content by as little as 5%.

I suggest a specific gravity test to see if it measures as a 90% silver coin should.

 

Thank you everyone, this makes sense and is what I thought, but wanted to be sure. Sorry for the thread hijack!

 

I ran the specific gravity test and am getting 10.307. That’s awfully close to the 10.31 I believe it should be, but I’m not sure what the allowable deviation is. Thoughts given this information?

 

I should have mentioned that even without a good SG, the coin appears to be "market acceptable" in terms of how these coins are judged to be "authentic" by most buyers and sellers.

That seems reasonable considering the silver content dropped to 89.6 % in 1785. If you really want to go the extra mile, an XRF reading that shows a small fraction of gold content would be the last measurement to conduct. Silver ore from the mines of Mexico all contain trace amounts of gold and the refining techniques of the time could not remove all of it so any genuine silver coins of colonial Mexico will show some gold content. My understanding is that even handheld XRF devices, sometimes used at jewelry stores or pawn shops, are sensitive enough to detect this small amount of gold.

You may ask "why would anyone counterfeit a common silver coin with the proper amount of silver?" The answer is that Chinese silver importers placed such a high premium on "CAROLUS" 8 reales that it was profitable through the beginning of the 20th century. You should read some of swamperbob's posts and his book for more details. Hopefully, he will comment on your post in CCF.

 

I’ve looked into a lot of swamperbobs posts and was hoping he’d comment on my other thread. Seems like a wealth of knowledge on the topic and I plan to buy his book for sure since my interest has really shifted to Spanish colonials recently. With counterfeits seeming to be abundant with this type of coinage, it seems necessary.