Suspicious Looking Mexican 8 Reales -- 1834, 1835 And 1896

Ah, noted. I did buy these coins on the pretense that they were cleaned or otherwise not original. I need a way to remove that polyurethane though!

Lacquer is very easily removed by acetone

I am sure Bob Gurney will chime in shortly.

Just noticed the title - the 1834 Do RM is likely the mule 365/371. Still check the die for an exact match with the 371. I recently discovered the THIRD different reverse die for 1834.

The 1832 and 1834 Durango coins were both produced in Europe (likely France). They were used in the French colonies and former French areas of the new world. That included Louisiana where large numbers of these coins were passed. They were made with a technology that was advanced compared to what Mexico or the US could do. John Riddell the refiner at the US mint in New Orleans believed the French had developed a method to create dies directly from coins. He wrote of this in 1844. I do not believe he was correct. I suspect that the dies could have indirectly come from the same parties who made the original hubs for Durango. The French makers of the hub had presumed that the Durango mint would be a long term customer. That is why the first two hubs were full date (1831). The Durango mint instead modified each die they made with new dates until the hubs fell apart. Because Durango did not buy any more 8R hubs, I would presume that the makers sold the hub making tools for the Durango design to cover their costs. These fell into the hands of counterfeiters. The counterfeits use exactly matching punches but the spacings do not actually match the hubs used in Durango.

As to why these counterfeits pass the tests you used - that is completely expected because of how the coins were made. They were mostly Sheffield Plate coins which consists of a fused metal sandwich of silver over copper or other white metals. The surface plates are 900 fine silver and they are relatively thick. Coins with intact plates are hard to spot and many have been encapsulated by the TPGs. Since the outer layer is good silver the coins pass most surface tests INCLUDING XRF. The best way to ID the coins is with the weight or Specific gravity. Both of these will be incorrect. The coins were made the correct size so the core makes them underweight.

I believe that your coin is likely silver over German silver. That combination was the most successful combination because the color change was not dramatic. So when the outer plate was worn off the core shows only a slight difference in color that resembles normal tarnish.

Not too many different combinations of metals work to make Sheffield plate. Both metals have to stretch at exactly the same rates or the attachment of the plate fails. Also striking of mismatched metals can make the plating loosen resulting in failure. Copper and German silver were both very good as was nickel.