1786 Keyhole & Porthole - NGC Certified

realeswatcher Thanks for showing some of the non-pristine examples of the same type. The easiest way to check a coin of this type (incorrect alloy) is of course SG. What I have noted is that most counterfeits are easy to detect with this method. Unlike the silver restrikes made for the China trade - these earlier counterfeits relied on a short assay to generate profits.

jgenn Your comment is worth looking at more closely. You say:




We know that coins as little as 15% short of silver were capable of returning a profit to counterfeiters who placed the copies into circulation. So some of these short on silver counterfeits could date to the original time of production - including someone doing it in the mint. This is one possibility - these would XRF as containing gold but SG would point to a shortage of silver.

Others made to pass to the Chinese to take advantage of the premium for Carolus coins from Mexico City could have been produced using accurate transfer technologies. These would have the correct alloy and density 10.31 but would be proven bad if XRF showed no gold.

Lastly it is possible (though I have never seen one of this exact type I can prove to be a pure Numismatic Forgery) that these coins could be produced from transfer dies made very recently. These would be proven only if there was no gold present and if certain recent additives were found on XRF - like cadmium added to most sterling silver to retard tarnish in the first decade of the 1900s and rare earth conductors added to silver and gold during the computer age post 1970. In these cases the source of the silver would be high tech recovery of silver in a modern refinery. These refineries often leave behind the more difficult to extract trace elements like those referred to above.

realeswatcher I do not believe I am casting doubt where none is warranted.

I cast doubt on the Keyhole porthole coins because I own several and at least one of each of the types I have described. Some are worn Sheffield plates where the silver has worn away exposing copper. These are scarce because the KH/PH wear off on many coins at the same time. But these are obvious counterfeits likely attributable to Birmingham. So there is noo problem with these since they stick out like sore thumbs.

The thickest "Sheffield" that I own is one of the very first that I discovered of the "key hole porthole" type (KH/PH). In that case the coin is a drilled example where the only visible copper is seen inside the drill hole near the center of the coin. In that one case, the center layer is not much thicker than the face plates and the center layer does not extend to the rim nor is there a covering ribbon applied to the edge. I am not certain it would be referred to as a typical Sheffield plate, but it is a sandwich of silver and copper bonded by heat. Normal Sheffield plate tends to be extremely thin plates (7 thousandths or so having been measured from a few detached pieces of plating). I have seen only one other similar copper sandwich and that was use to make a Guadalajara coin in the Cap and Ray series. I suspect they were most likely created as three cast layers with the copper disk being cast separately and placed on a mold partially filled with silver and then covered with molten silver. This method would not be a mass production technique but it is simpler than Sheffield Plate that requires specialized equipment. The actual composition remains conjecture because in neither case have I cut the coin in half to be positive. I also value these two oddities at far more than the typical counterfeit precisely because of how they were made. (I also collect by metallic composition and these two examples are extremely rare - with only one type being rarer a unique type using thin slivers of silver embossed with the design of a genuine coin over a core of copper - ex: Mike Ringo also in my book). This type is also not a problem since SG discloses it easily.

There are however numerous other examples of the KH/PH that are struck on debased silver planchets that are once again easily detected simply by determining the SG. SG under 10.29 is a fraudulent coin. Fortunately the ones I have discovered all into the 9.6 range. Those are also extremely easy to spot.

The examples found in the Postal Commemorative holders are known to originate in China. They are possibly brand new NF or they were made for China copies from the 1880-1930 period. Of the pictures you post only two coins are clearly modern copies using technologies employed in China now. These are the 1797 at the top and the 1789 at the bottom. They are melt coins worth little more. I believe they are modern NF types based on visual traces alone. I have never tested any of those with a lab level XRF machine to determine if they do or do not contain any of the trace contaminants like the 1910 marker of Cadmium or the 1970 marker consisting of the rare earth metal traces or any of the others I am aware of.

In my opinion, the only iron clad proof of a modern silver fake ultimately becomes a lab level XRF test. It is very possible to artificially treat this class of forgery to remove all the remaining surface clues like the edge arc, the MS edges, the artificial color and the surface blemishes that proves they are forgeries visually. If left with a worn cleaned up example - only a costly lab level XRF ($50 up per test) will suffice.

You also need to recall that ultimately there is no test that proves beyond all doubt that a coin is genuine. All you can do is to use various tests to eliminate different known classes of counterfeit types.

Surprisingly, at least to me, you say:




I agree completely that some KH/PH coins are clearly a solid alloy - either genuine silver refined and struck in Mexico on the date stipulated on the coin or one that is debased, struck elsewhere and on a different date which does not wear through or provide other visual clues. That is precisely the problem. What surprises me is that it does not seem to bother you to call a silver restrike made for China an original. This is particularly bothersome if it can be easily proven to be bad. Or are you questioning the very existence of the entire class of made for China silver frauds?

I am really suggesting that every 8R should be tested by weight first, SG second and XRF (handheld) for gold third. Not just keyhole porthole types but all Mexico City types. The fourth step of using lab level XRF is more limited due to cost but will reject coins as fakes that otherwise have no convincing clues.

No Mexico City 8R is above some level of suspicion except perhaps members of a hoard known to come directly from a mint shipment; and in that case it must be demonstrated that no coins were added to the original shipment or swapped out.

The castle windows in question, observed on a piece stated by Sedwick to be from the wreck of the Lutine (1799)... along with several other pieces from said provenance in that sale with similar surfaces:

https://www.icollector.com/Mexico-C...9F_i29835833

This is the only confirmed contemporary wreck/hoard piece showing these castles I find in online archives. A lot of the Worthpoint pages for the Haiti Hoard pieces of these dates sold by southfloridacoinscollectibles don't have reverse pics available.

A few more 1786 finds:

Cleaned 1787 AU in NGC plastic - might go cheap.

https://coins.ha.com/itm/mexico/wor...2052-21014.s

Currently on eBay in an error PCGS holder improperly cataloged as 8 Escudos:

https://www.ebay.com/itm/1788-Mo-FM...AOSw1Ylfz7R8

PCGS Cert Page: https://www.PCGS.com/cert/28256749



Here's an interesting feature on the reverse of this one:

PCGS certified with BOE octagonal stamp

Did you know Stacks Bowers is having an auction featuring GREAT BRITAIN. Great Britain - Mexico. Dollar, ND (1804). George III. PCGS EF-45 Gold Shield; Countermark: VF Details. as a lot item: https://play.google.com/store/apps/...stacksbowers

I think there are enough authentic examples of the G3 stamps, both octagonal and oval, which gives us a location and point in time.