Counterfeit Detection: 1783 Mexican 8 Reales

Posted on 2/1/2020

A minor date change exposes this coin as an altered specimen.

By Numismatic Guaranty Corporation®

In 1783 the Mexico City Mint struck hundreds of thousands (if not millions) of 8-real coins. Unfortunately, the actual mintage figures have been lost to time. What is known, however, is that two different varieties were struck that year, each corresponding to different assayers, FF and FM. These initials can be found on the reverse at the 10 o' clock position.

This 1783M̊ FM reales recently was submitted to Numismatic Guaranty Corporation (NGC). A quick search in NGC's World Price Guide ( reveals that this is an exceptionally rare issue. An example in Very Fine-20 sells for a whopping $9,000, while the more common FF in the same grade goes for only $150.

An initial examination shows nothing amiss with the M, so the coin appears to be genuine. However, more common issues with the FM mark were struck in different years. A closer look at the date reveals the deception; the 8 almost certainly has been altered. As you can see from the photographs, there is an odd discoloration around the numeral. Additionally, both the top and bottom loops are full of fine toolmarks from the forger's attempt to smooth them out. This same tooling can be seen around the outside of he digit as well. This coin likely started as a 1773M̊ FM 8 reales. With one small alteration, it appears to be worth thousands of dollars more.

While the assayer's mark (right) on this 8 reales is correct, the date is not. Close examination reveals toolmarks and discoloration around and inside the loops of the 8. This coin most likely is an altered 1773 example, which is much more common.
Click images to enlarge.

When purchasing a key-date coin, it is important to closely examine those parts that make it special (in this case, the date and assayer's mark). If you are unsure of your authentication abilities, purchase a coin already graded by NGC, as it is guaranteed to be original and unaltered.

The altered 1773M̊ FM 8 made to look like a 1783M̊ FM 8
Click images to enlarge.

Reproduced with permission from the October 2019 edition of The Numismatist, official publication of the American Numismatic Association.

Did you know? NGC has created a comprehensive Counterfeit Detection resource to help collectors and dealers identify counterfeit and altered coins. Visit

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