20021sc So the answer is incuse. Not great news for the case that the coin is genuine. That needs some explanation but first a couple points of clarification.
I saw this coin on
ebay when it was initially offered and I recorded it at the time. I was suspicious of it possibly being an electroplated fake. Of course it sold for far more than I would ever choose to pay for any encapsulated counterfeit but I wanted to watch the bidding.
This thread is one I had missed initially. I have been sick for a couple weeks after my surgery and I am just now getting back to work starting yesterday. I had missed the thread until John Lorenzo wrote to me about the coin. He is the person I quoted at the top of my initial comments. His initial impression and mine matched.
So my comments here were really due to his question.
Since John and I both saw the coin as a potential counterfeit independently, I think we need to be very clear about why. To do so I need to summarize the history of silver counterfeiting over the period prior to the 1860s, which is the earliest date at which this coin could have been produced.
This will be long, however, I will eliminate all but needed details. Too brief and confusion may result.
In antiquity a counterfeit silver coin was either struck or cast. Struck counterfeits were typically simple debased silver. Casts counterfeits were also debased silver. The products were usually boiled in an acid to improve the surface color by removing some of the surface copper.
The problem with these methods was too much silver was used. Coating techniques were developed as a result to save costs. Painting a struck or cast base metal copy was done with mixed results. They also used silver amalgam plating where powdered silver was mixed with mercury forming a paste which was applied to base metal copies. The mercury was then driven off by heating the fake leaving a coating of silver (it is like gilding but far harder to accomplish). Silver gilding was not very successful.
Finally and most successful was a discovery that a planchet of copper could be struck between two silver foil sheets producing a decent bond. The technology was first used on coins manufactured by the State but of course counterfeiters soon adopted it. This is the origin of the ancient fourees.
Not much changed in counterfeiting for centuries.
In the 1700s the newly rediscovered sciences led to new techniques. The first discovery was actually Sheffield Plating (ca 1770) mentioned by John Lorenzo. The discovery was accidental and it demonstrated that silver alloys could be melted onto copper and when the cooled ingot was worked both layers acted as if they were one metal. The two metals expanded and contracted as a unit and could be struck and bent with little fear of the copper breaking through.
This lead to experimentation with other metals but most combinations did not bond well.
When a counterfeit is made of silver over a core of base metal the materials used must be compatible. Most metals and alloys bond poorly and eventually separation along the joint is the result. Copper and silver are two metals that bond very easily one to the other. Most metals other than gold and a few alloys are not compatible with silver and as a result the surface silver tends to detach and may break away. Scientists knew this fact, but forgers initially did not. Therefore forgers often used copper alloys which often resulted in corrosion between the layers. Many of the most easily discovered contemporary counterfeits fall into this category.
Bonding the silver to copper using heat creates a metal sandwich that can be rolled out. This way a very thin silver layer over copper can be produced. This is Sheffield Plate the process introduced in the 1770s. This method dominated in the manufacture of successful forgeries for almost 6 decades. Earlier Sheffield Plates can have rather thick silver layers but over time and certainly by 1820 a plate of only 1 or 2 thousandths could be produced. The beauty of Sheffield Plate for forgery was the color perfectly matched coin silver because it was coin silver 900 to 925 fine. Sheffield Plate could pass acid surface tests, as well as tests in which the coin is rubbed on a touch stone. If a counterfeit was slightly enlarged in volume even the weight could be made correct. Even chopping did not always detect a Sheffield Plate coin with a thick silver layer because the silver flowed along with the copper. The best detection method for detection of Sheffield Plate coins was and still is Specific Gravity.
Sheffield Plate had no competition at all for counterfeiting until the arrival of German Silver. This alloy was first produced in Germany ca 1832, England ca 1835 and the US ca 1837.
As an aside, I should note the following:
A metal called Paktong or Chinese white copper was imported from China to England in colonial times. Export of the metal was illegal under Chinese law, so most of the Paktong in the west was smuggled out. As a result it was even more popular among English gentry than sterling silver. At times items made of Paktong sold for more than did sterling. Paktong is very similar to German Silver and at the present time, the alloy falls into the generic category of "german silvers". However, in the 1820s it was seen as a different metal. Costs of Paktong in England were too high for the metal to be available to counterfeiters except in very tiny amounts derived from jewelers scrap. German Silver (Capitalized to distinguish the German variety from generic alloys) is the technology discovered in Germany. Many of these metals can be isolated from Paktong based on analysis techniques developed at Whinterthur Laboratories. These tests rely on a database of trace contaminants known to be present in Chinese metals. Winterthur Labs uses the trace contaminants to authenticate Museum Level rarities. The tests are simply too expensive to be used for most counterfeit coins.
Sheffield Plate briefly survived for forgery because the color of German Silver was generally too dark after a period of time exposed to air.
Sometime not long after 1835 and certainly before 1845, some unknown counterfeiter discovered that silver would bond to German Silver almost as well as pure copper and far better than bronze or brass. This resulted in a counterfeit that has coin silver over GS leaving a more subtle color change than silver over copper. Most of the later Sheffield counterfeits use a lighter GS core. The technology is distinctive.
The next technology developed was electro-plating. This was first encountered accidentally in a lab about 1840 or 1841 as I recall. The technology was first successfully used on an industrial scale to coat metal about 1845. Riddell in his 1845 book is familiar with the new technology and indicates some of the counterfeits he discovered were most likely electroplated.
At about the same time, electrodeposition was discovered and was used to create duplicates of copper coins initially by depositing copper electrically on an impression of a coin made in fine wax-like substance. This material worked because it could be coated with a dusting of carbon to make electricity flow. The process does not generate enough heat to melt the impression so electro-typing is unlike casting. Two thin shells of copper are created. The halves are filled and soldered together. The impression developed was Museum quality but there is an edge seam that must be hidden. Depending on the fill used, electrotypes are normally the wrong density.
This means that a counterfeit produced in the 1850s or later could have been made using any of these methods and materials.
The three most likely possibilities are Sheffield Plating, Electro-plating or possibly Electro-typing. I need to do some research to see precisely when electro-plating in silver was first used but I feel safe it was done before the mid-1860's.
Now we need to address how corrosion or damage could have occurred which would produce the recessed effect seen on this coin. The bad news is that based on the pictures and the confirmation that the features are incuse, the coin is VERY UNLIKELY GENUINE.
The suggestions proposed in your last comments include post-strike damage to the coin, pre-strike die damage and corrosion due to contact with dirt in a burial of some sort. None of these suggestions are adequate to explain the appearance, which unfortunately is very familiar to anyone used to studying counterfeits.
Post-strike damage is seen today on many coins at the perimeter due to coin counters. There were no coin counters until the last quarter of the 19th century. Most mechanical means would show a drag in the direction of the cause. I cannot postulate a mechanism that could produce what I am seeing here.
Pre-strike die damage is extremely unlikely because the die would need added metal in the depressed features only. Again the mechanism needed to do that without effecting central detail escapes me.
Electroplating is normally done to a completed item. The coin was not coated with silver plate that is obvious in the pictures. It could be a planchet electroplated and then struck. The main drawback is that the features that are seen on a struck electroplated planchet are just not seen here.
Finally erosion of isolated high points by ground contact. This normally results in corrosion that is not seen on high points alone but over large portions of the surface. Placing a coin on a wet conductive flat plate might produce such damage if a current was passed through the plate but that should also involve all high point contacts not just at the perimeter.
Platings of all sorts will produce micro-currents that flow between the surface coat and the core. In silver plated objects the corrosion occurs in the base metal not the less reactive surface layers. This corrosion undermines the surface layer while leaving the surface intact. The corrosion is not seen until the silver is knocked away by pressure. This is unfortunately what I see here.
I would suggest that you contact PCGS directly and explain that you just purchased the coin but you have serious misgivings that the coin may not be genuine. Ask them to verify their initial authentication after you advise them of our comments. If they want to talk to me before you send the coin to them, I can provide my contact information, because I want to know for certain as much as you do. Any technology that could produce such a copy is dangerous and they should be professional enough to examine the situation objectively. You could do that as part of re-holdering the coin. Re-holdering of damaged slabs is a service they offer at a very small charge. Then while the coin is out of the holder, they could do the needed testing to make a scientific determination. If the coin is genuine you get it back in a new holder. If it is a fake, they will follow the chain of ownership backwards and PCGS will make good on your losses.
Posted 01/03/2018 8:29 pm
. Time would be better spent learning what is to be expected on Chihuahua issues of the 1850s-60s.
