Class 1 Or Class 3 Counterfeit? Please Judge!

I think the key is accuracy of the SG test. I am of course presuming that the test was done accurately when I make comments about the coins.

An error at this point would negate EVERY COMMENT made up to this point.

The only way to get a low SG for a correct regal alloy is for the coin to be partly hollow (contain air) or for the alloy to contain elements not seen by XRF tests.

The XRF results totalled 99% of weight so a light element is ruled out.

The mint procedures of pouring small fillets which are then rolled - drawn (laminated) - blanked and struck will eliminate most internal voids. Some do occur but what is postulated here is a void that does not approach the surface at any point. Possible of course - just unlikely.

Post strike drilling seems to rule itself out because the coin is still the correct weight and the volume (exterior shell) is unaltered.

For me, the best answer is usually the simplest answer (Ockham's razor). The SG is low because the alloy is incorrect at the core. XRF reads the surface only.

How the coin was made to produce that effect needs to be determined.

Makes me wonder if that area around REX is surface peeling?

Need bigger pics from afar to verify whether that's something missing there as opposed to something growing, but that looks possible. Perhaps would have been a good spot to zap...?

The full XRF results of Coin A and B: (I suppose other elements are not important for our interpretation so I didn't show all last time)

Coin A: Cu7.54, Pb0.31, Ag90.29, Zn0.04, Ni0.02, Fe0.08, Bi0.06, Tin0.24, Pt0.79, Au0.15

Coin B: Cu3.11, Pb0.45, Ag94.4, Zn0.02, Ni 0.01, Fe0.08, Bi0.05, Tin0.27, Pt0.89, Au0.24

When I re-examine Coin B, I find two small sharp cuts at one side of the edge. Were the clips being used for Ag content analysis? Who knows? If one really did, it would not be a Chinese because Chinese used chops to identify the authenticity of a coin. Just a side talk here, please see the pictures below:



I think this will be one of the most controversial threads to some experts of this forum. Do you remember, swamperbob, before the result of XRF, you said:
The A coin is Genuine.
The B coin is a Numismatic Forgery.

After the XRF results, you said:
...But both coins also have INCORRECT EDGE DESIGNS. That would indicate both coins were made OUTSIDE the mint by a counterfeiter....At this point we have ruled out both Class 1 and Class 2.

By colonialjohn:
...So with Coin B with Ag at 94.4% and good Pb, Pt & Au levels this is not a modern piece and its either Class 1 or Class 2.
...So when I analyze a coin and the silver value >90% with good Pb, Pt & Au I am thinking Class 1 or Class 2.

Frankly, I have no idea about the edges of both coins are regal or not because among my 30+ Portrait 8R, I have only these two New Guatemala 8R so I have no ground to argue about the edge of coin A and B.

But by XRF results, the level of Pt and Au, they prove that coin A and B are aged coins, not modern.

For the high similarity in appearance of both coins, I tend to believe they were struck from the same die and as direct transfer of an image existed after 1830, it makes me believe they were produced from the same mint before 1830?

Could both coins be produced after 1830, say 1865, as a numismatic forgery? Never! ~as this 1820 8R is not any sort of rarity. As a circulating counterfeit? Yes, especially for coin B! If the latter is the scenario, where would it be struck? Anywhere outside N.G.? Probably, then why the counterfeiter not struck for a more popular Mexico 8R?

For the two actual coins on hands and the results of XRF, they make me feel coin B is more likely a debased original than Class 2 or Class 3 counterfeits and coin A is likely be an original. Realeswatcher's choice B is what I think the most likely scenario.

Of course it is better to have a real original 1820 8R for a comparison between the two coins, otherwise, this becomes a phenomenon of belief or disbelief, that is another "fun" to the hobby of coin collection.

P.S.
I don't remember where I read, Fred. VII's portrait coins were really not as popular as Car.IV or Car. III's for the reason at Car. IV's time, Chinese enjoy a more peaceful time than the early 19th Century. So Chinese people loved Carolus more. Probably another unproven reason, Carlous portrait looked more likely a buddha, that was why he was more popular than his son. A debased Ferd. VII 8R of New Guatemala has zero chance as a circulating Class 2 counterfeit in China, I suppose.