8 Reales Counterfeit Detection

This promisses to be an excellent topic, from which we will all learn.
Swamperbob, Dosmundos, that one is for you :)

Gilboy illustrates a single matrix block in his book which was used to make punches for portrait dies NOT for the earlier Columnario types. The earlier type was at times made with a fractional punch so that some overlaps do appear.

Information like the punch configurations must always be studied in the context of the production of one mint. At Mexico City the press used to set the King Punches for the Portrait series was in fact large enough to set the entire shield outline. But the inner segments were initially distinct features. Caution must always be exercised when only one feature is being used to PROVE a coin is a forgery. One feature clearly raises a suspicion of forgery but proof (confirmation) should always come from an alternative source. For instance a bad edge, and low SG combine to paint a very bad picture while a few die anomalies in shapes could be the result of a repair after a lap or even a partially set King Punch.

I think you may be reading more into the discussion than was intended. Any reference to the matrix block illustrated in Gilboy MUST pertain only to the Portrait series made after 1772. Any other reading would likely be an oversite.

I also agree that Potosi at times made some very crude shield outlines. Why? I do not know. I have not studied them long enough to postulate a working theory. But off the top of my head I can come up with a half dozen possible causes. What we know with great certainty is that procedures were not 100% identical at the branch mints at all.

I am sorry there is no simple answer about all these questions, but not enough hours have been spent yet gathering the necessary data. We are still at a beginning stage.

Calbetto has made some mistakes in his classification but mostly with portrait coins. He has clearly placed all counterfeits both contemporary and modern into ONE single group. This causes confusion.

There are about a half dozen war time Portrait 8Rs that I personally believe may be contemporary forgeries but neither Calbetto nor Gilboy seem to have counterfeits shown as genuine in the Pillar types. I am of course far less familiar with those coins and I might be missing some there.

Pat, it is good that you have your eye out for detail... Like Bob said, the fact that there was at least some use of a single-punch rectangular shield (for portrait coins) as shown in Gilboy can't be taken as gospel for what happened at ALL the various mints, or back to the Pillar 8R (with mint to mint variety present there, too, of course).

Observations on this point from a few years ago:
https://goccf.com/t/70191#560115

I will note that I own a 1770 Potosi with similar overlaps at the upper corners of the shield, which seems to indicate that the shield was pieced together rather than applied as one punch. That effect is also clear on the 2nd piece jfransch showed, plus on this piece, shown in a follow-up thread:
https://goccf.com/t/70914

Studying enough pieces like that, it starts to become clear that the pillar 8R shield was NOT single-punch on at least some genuine emissions, or some emissions out of Potosi anyway. What Bob said are my thoughts exactly:



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Boy, that's cynical even for me!!