If the listed weight is 27.07g, how far below that would you be willing to accept as an authentic coin? (ignoring all other counterfeit diagnostics)
Certainly no less than 25 grams. I don't know a whole lot about weight tolerance but anything in the 24 gram range or less would be way to much tolerance. Do you have a specific weight value in question?
It depends on the amount of wear. There is no specific weight that would signify the coin is fake unless of course it is MS or AU and weighs over 29g or less than 25g.
It's a lot more complicated than that. The maximum and minimum permissible weights for any of the coinage of the Spanish colonial mints was always established by Royal Decree. As was the degree of fineness. And they were very strict on this, strict to the point that violation could end with execution. That said, the specific time period being discussed also has a bearing. For example, during the cob period coins always had an established minimum & maximum weight tolerance, and a fineness, but the very nature of the coins led to clipping which was a pervasive practice. As a result of this the weight of surviving coins is all over the map and the weight is almost never used to determine authenticity, because it cannot be. With the advent of the milled coinage in 1732 things changed. Milled coinage put an end to clipping, so the weight can be used to determine authenticity. With milled coinage the maximum permissible weight for an 8 reales was 27.2638 grams. The minimum was 26.8646 grams. That is a very strict tolerance level and yes they did indeed use 4 decimal places. And these tolerance levels applied to all mints. Now contrary to what a lot of people think loss of weight due to wear is almost a non issue. That is because there is no appreciable loss of weight due to wear until you get to very low grades like VG. Even coins in F have no appreciable loss of weight. There is however the issue of deliberate underweight coins with coins from Potosi and from a specific time period. These coins were deliberately minted and struck underweight by mint officials. And they were caught, and some were executed, others were punished in other ways. But the underweight coins still exist. So short and sweet, in some cases weight can be used to determine authenticity and in some cases it cannot be used. And you have to know all of this information to know which is which.
Normally weights this high tend to favor an authentic coin assuming a good edge and appearance. Counterfeits are normally at regal weight and below. John Lorenzo United States
In the new GNL book at Amazon Books now released the recommended cut-off is 25.0 grams for all mints which is discussed in detail in this 600 page book for $40 <BG>. JPL
1778 Mexico carolus dollars are known to have debased fakes that were done by us british villains in canton.
That maybe what is listed in the book you reference. But the numbers I listed above are what is listed in the Royal Decrees that still exist in the Spanish archives today.
Just to echo GDJMSP, I think we need to be a bit more nuanced with what an acceptable weight range for 8 reales coins is. It is absolutely correct to say that a milled, non shipwreck, 8 reales coin should not be below 25 or 26 grams - even in low grades. However, there are other considerations. Shipwrecked 8 reales coins, which are fully certified and sold by reputable dealers, are regularly sold at weights as low as 20 grams - in both milled and cob varieties. There is also the issue of the Potosi mint in the 1600s, where 8 reales were debased by reducing silver content and clipping. Most of these coins were tracked down and destroyed, but many also survived. So if your coin is milled, and looks complete, it should be 26 - 27 grams. If it's not milled, and/or is a shipwreck coin, the minimum weight can be much much lower.
Yes - this information jives withe book. So for a normal 8R anything below 25 grams is probably debased with copper. I say debased only since predominantly brass or copper alloys are very easy to verify - of course and the point of them being authentic is even moot.
In short and from my experience, any milled 8 reales, columnario or bust, (not macuquinas) under 26,3x g. have high probability (+60%) of being not autentic (VF grades and up). Of course, there are reales de a ocho not authentic with appropiate weight as well. ps Linked thread https://www.cointalk.com/threads/8-reales-spanish-empire-and-peninsulars-for-all.258294/page-4
https://moneditis.com/2015/03/10/8-reales-de-busto-de-subasta-falsos-i/ Weight: 26,77 g R.M.S.: 0.000 Sum before normalization: 102.8 % Normalised to: 100.0 % Element Conc.(%) 1 Ag 92.58 2 Cu 2.81 3 Cl 2.27 4 Na 0.95 5 Ca 0.40 6 Si 0.38 7 S 0.21 8 K 0.13 9 Al 0.12 10 Pb 0.09 11 Mg 0.05 12 P 0.02 Not authentic More https://moneditis.com/2015/03/11/8-reales-de-busto-de-subasta-falsos-ii/ https://moneditis.com/2015/03/12/8-reales-de-busto-de-subasta-falsos-iii/ https://moneditis.com/2015/03/13/8-reales-de-busto-de-subasta-falsos-iv/ https://moneditis.com/2015/03/16/8-reales-de-busto-de-subasta-falsos-v/
