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Shocking Experience from CGS - Coin Grading Services - Forum Advice Pl

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Verd can be on any coin even as a loose particle that has been passed on from another and with grading companies they have different tollerances as to what is acceptable.

The main problem is when the verd has got into the metal which in some cases will cause corrosion and damage the surface of a coin.

I was quite surprised to see the coin above ,so have blown the images up from the UIN 5854 that Eric sent me.

Looking at blown up pictures of the coin which was pictured before being slabbed i cant see anything at all ,so feel it has changed since it was graded.

Edited by PWA 1967

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Perhaps verdigris formation should be seen as part of the  minting process of 50% silver coins as it is most probably due to incomplete melting of the component metals as copper melts at a higher temperature than silver. In theory this should not happen if the alloy is properly made. As for bronze coins the metal used is inherently subject to attack. 

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38 minutes ago, PWA 1967 said:

Verd can be on any coin even as a lose particle that has been passed on from another and with grading companies they have different tollerances as to what is acceptable.

The main problem is when the verd has got into the metal which in some cases will cause corrosion and damage the surface of a coin.

I was quite surprised to see the coin above ,so have blown the images up from the UIN 5854 that Eric sent me.

Looking at blown up pictures of the coin which was pictured before being slabbed i cant see anything at all ,so feel it has changed since it was graded.

I am sure the verd has developed after slabbing. CGS initially didn't grade coins even with a trace of verd. Then I think they have relaxed that rule for rare coins with very low grades like CGS4

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25 minutes ago, ozjohn said:

Perhaps verdigris formation should be seen as part of the  minting process of 50% silver coins as it is most probably due to incomplete melting of the component metals as copper melts at a higher temperature than silver. In theory this should not happen if the alloy is properly made. As for bronze coins the metal used is inherently subject to attack. 

Verdigris is damage which occurred after the minting process and so not can't be part of the minting process in my view. 

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True, except that there may be surface alloy problems with metals that are more reactive I would think. 

 

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img1.jpg

img2.jpg

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6 hours ago, VickySilver said:

True, except that there may be surface alloy problems with metals that are more reactive I would think. 

Agreed. But the truth is that even a bronze or copper coin would not develop verd if it has been properly handled and stored.

Your 1935 crown has been problem free for ca 70 year. Then presumably a bit of carelessness such as a tiny saliva spot could have started the process off. 

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If you notice it's a chunk of foreign matter with verdigris radiating from it. So a speck of some oily corrosive material, almost certainly biological,  has landed on the coin,  during or just before slabbing, and started its insidious effect from there. Unfortunately that spot may spread out further over time, unless that central lump is removed.

 

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26 minutes ago, Sword said:

Agreed. But the truth is that even a bronze or copper coin would not develop verd if it has been properly handled and stored.

Your 1935 crown has been problem free for ca 70 year. Then presumably a bit of carelessness such as a tiny saliva spot could have started the process off. 

Ah, now that's interesting. I know that saliva droplets cause carbon spots to develop. So why - scientifically speaking - would one droplet of saliva cause a carbon spot, and another cause verd to develop?  

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I understood carbon spots to be a misnomer as they are caused by sulphur deposits, car tyre dust, some old paper sources etc. Verdigris is produced by an acidic reaction, salts in wines, urine, sweat skin etc. Bearing in mind that Verdigris can turn black over time. Verdigris was made as a pigment in past times.

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1 hour ago, 1949threepence said:

Ah, now that's interesting. I know that saliva droplets cause carbon spots to develop. So why - scientifically speaking - would one droplet of saliva cause a carbon spot, and another cause verd to develop?  

I don't know the details but agree with Diaconis that the term "carbon spots" is a misnomer. Both "carbon spots" and verdigris are substances formed in the corrosion processes of copper. 

Copper compounds such as basic copper chloride, copper carbonate, copper acetate etc are green and hydrated mixtures of such can be called verdigris. Other copper compounds such as sulfides are black. Silver sulfide is also black.

Water is important in the corrosion of metals. One reason is that the formation of a copper compound from copper is an oxidation process and involves the loss of electrons. Water allows the movement of electrons. 

But I am just speaking from a general viewpoint and have never looked into this in detail. 

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32 minutes ago, Sword said:

I don't know the details but agree with Diaconis that the term "carbon spots" is a misnomer. Both "carbon spots" and verdigris are substances formed in the corrosion processes of copper. 

Copper compounds such as basic copper chloride, copper carbonate, copper acetate etc are green and hydrated mixtures of such can be called verdigris. Other copper compounds such as sulfides are black. Silver sulfide is also black.

Water is important in the corrosion of metals. One reason is that the formation of a copper compound from copper is an oxidation process and involves the loss of electrons. Water allows the movement of electrons. 

But I am just speaking from a general viewpoint and have never looked into this in detail. 

Thanks.

I do know that "carbon spots" (be that a misnomer or otherwise) are very common on bronze/copper coins which are close to uncirculated. Often multiples on the same coin, some tiny, others much larger. They seem to disappear if the coin is circulated - a process I know obviously occurs, but I've no idea what the explanation is. Nor why they never seem to appear on coins once circulated. Does the handling of circulation and the build up of other matter on the coin's surface lend some protection against this, I wonder?  

Whereas verd can appear on any coin, circulated or not.  

ETA: Interesting article

 

Quote

 

Over time, copper and bronze coins will naturally change color from mint red to various shades of brown as a microscopic layer of oxidation covers the surface. This is good for the coin. The oxidation forms a protective barrier against harmful substances that could literally eat into the surface. Mint red copper and bronze coins offer a "fresh" and fragile surface that is more vulnerable and susceptible to spotting.

Under magnification, it is not unusual to find some minuscule flecks of discoloration on red, and red and brown coins that have been graded MS-64 or higher by a grading service. If your goal is to locate absolute mint red large cents with pristine, spot-free surfaces, you may be in for a very long hunt. Even in the case of modern issues, like pre-1960 Lincoln Cents, tiny spots may be found on high-grade examples.

There are many substances that can create spots on coins. Moisture from breath or, heaven forbid, an innocent sneeze can eventually do tremendous damage. I knew one old-time dealer who enjoyed lighting up a cigar while viewing coins. I wonder how many of today's coin spots are the result of his exhaled tobacco smoke?


 

Another observation (please feel free to correct me if I'm wrong, as I'm manifestly no expert on this topic) - verd seems to be contagious to other coins in contact, whereas "carbon spots" don't. Nor does a single carbon spot spread to other areas on the same coin, unless a separate incident occurs, unconnected with the appearance of the first. Not as far as I'm aware anyway. So there does seem to be a significant difference between the two, both in scope and effect?  

Edited by 1949threepence

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I imagine the surface of a verd spot is more flaky in nature. The deposit of a tiny speck of the green stuff, can I suppose, provides a new site for another verd spot to form?

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21 minutes ago, Sword said:

I imagine the surface of a verd spot is more flaky in nature. The deposit of a tiny speck of the green stuff, can I suppose, provides a new site for another verd spot to form?

Indeed - sounds as viable a possibility as any.

Interesting topic.

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3 hours ago, Diaconis said:

I understood carbon spots to be a misnomer as they are caused by sulphur deposits, car tyre dust, some old paper sources etc. Verdigris is produced by an acidic reaction, salts in wines, urine, sweat skin etc. Bearing in mind that Verdigris can turn black over time. Verdigris was made as a pigment in past times.

I've always assumed verdigris was also known as ""carbon spots" because it is principally copper carbonate, which is that characteristic green colour, formed by reaction of the copper with oxygen and carbon dioxide (that's where the "carbon" bit in the carbonate comes from). The formation is catalysed by moisture (like the formation of rust), so keeping coins dry will inhibit its formation. As I said above, I think foreign matter landing on the surface has caused the verdigris plus perhaps Nickel reaction in this case. 

Seriously though, CGS should rigorously check the surfaces are speck free before sealing the slab. I think they should give a refund for this.

 

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I think the term "carbon spot" probably refers to the appearance of the black spots and not to the chemical composition. i.e. carbon is black and so the spots looks like bits of carbon. Verdigris has never been called carbon spots as far as I am aware simply because it is green. 

"CGS should rigorously check the surfaces are speck free before sealing the slab. I think they should give a refund for this." Unfortunately, their quality control was rather poor from experience. I have used them to slab a few coins some years ago. One came back with a tiny bit of plastic on the top of the legend. Very irritating. Several slabs were scratched or had minor cracks. 

With regard to the1935 crown in question, it has been looked after properly for ca 70 years. Then a horrible verd spot suddenly started to develop after the CGS slabbing. I am sure the thought that CGS might have something to do with it has crossed VickySilver's mind.

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4 minutes ago, Sword said:

I think the term "carbon spot" probably refers to the appearance of the black spots and not to the chemical composition. i.e. carbon is black and so the spots looks like bits of carbon. Verdigris has never been called carbon spots as far as I am aware simply because it is green. 

"CGS should rigorously check the surfaces are speck free before sealing the slab. I think they should give a refund for this." Unfortunately, their quality control was rather poor from experience. I have used them to slab a few coins some years ago. One came back with a tiny bit of plastic on the top of the legend. Very irritating. Several slabs were scratched or had minor cracks. 

With regard to the1935 crown in question, it has been looked after properly for ca 70 years. Then a horrible verd spot suddenly started to develop after the CGS slabbing. I am sure the thought that CGS might have something to do with it has crossed VickySilver's mind.

Well it does seem a remarkable co-oincidence for one to suddenly pop up after 70 years, post slabbing.

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12 minutes ago, 1949threepence said:

Well it does seem a remarkable co-oincidence for one to suddenly pop up after 70 years, post slabbing.

I have brought a CGS slabbed 1937 proof crown from Lockdales using the CGS photos years ago. When I have got it, there's a carbon spot by the King's nose which is not visible in the CGS photo. The thought crossed my mind alright. 

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Surely coal fires and candles were instrumental in spotting many coins. Collectors of old poring over their collections by candle or lamplight in a room with a coal fire. All recipes for disaster. The soot particles from all those fossil fuels in in our collectors living room are a mix of  metal oxides, minerals which may can be coated with weak  sulphuric acid. Nutty slack and precious metals are not good bedfellows. 

Regarding the coin in question, contamination must’ve occurred during slabbing. I’m not even sure if it is verdigris but the contaminant definitely contains a reactive agent all the same. Would be interesting to have it analysed.

I’d certainly crack it out of that slab and remove the offending object before it causes more damage. It’ll only get worse.🙈

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Contamination is not the prime cause corrosion. For corrosion to take place cathodic and anodic sites must be present on the surface of the coin and the contamination aids the conduction of electricity between the two sites causing a chemical reaction and thus corrosion. In this case the Cu has not melted properly because of its higher melting point and along with Ag forms the other half of the corrosion cell with a potential of 0.28 v between them ( Cu. valency 1, cupric). If the alloy for the coin blanks had been properly prepared the corrosion would not take place despite the presence of contamination on the coin. Of course removing contamination from the coin's surface prior to slabbing would be a good idea and should be given some thought by TPGs. Given this verdigris is as a result of the manufacturing of the coin blanks prior to the minting process not the slabbing. Of course it is still unsightly and damaging to the coin. In conclusion the seed for corrosion was planted in the coin long before it was slabbed.

Edited by ozjohn

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2 hours ago, ozjohn said:

Contamination is not the prime cause corrosion. For corrosion to take place cathodic and anodic sites must be present on the surface of the coin and the contamination aids the conduction of electricity between the two sites causing a chemical reaction and thus corrosion. In this case the Cu has not melted properly because of its higher melting point and along with Ag forms the other half of the corrosion cell with a potential of 0.28 v between them ( Cu. valency 1, cupric). If the alloy for the coin blanks had been properly prepared the corrosion would not take place despite the presence of contamination on the coin. Of course removing contamination from the coin's surface prior to slabbing would be a good idea and should be given some thought by TPGs. Given this verdigris is as a result of the manufacturing of the coin blanks prior to the minting process not the slabbing. Of course it is still unsightly and damaging to the coin. In conclusion the seed for corrosion was planted in the coin long before it was slabbed.

(Cu valency 1 is cuprous, valency 2 is cupric).

Anyway, my main reaction is...uhhhh??

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7 hours ago, ozjohn said:

Contamination is not the prime cause corrosion. For corrosion to take place cathodic and anodic sites must be present on the surface of the coin and the contamination aids the conduction of electricity between the two sites causing a chemical reaction and thus corrosion. In this case the Cu has not melted properly because of its higher melting point and along with Ag forms the other half of the corrosion cell with a potential of 0.28 v between them ( Cu. valency 1, cupric). If the alloy for the coin blanks had been properly prepared the corrosion would not take place despite the presence of contamination on the coin. Of course removing contamination from the coin's surface prior to slabbing would be a good idea and should be given some thought by TPGs. Given this verdigris is as a result of the manufacturing of the coin blanks prior to the minting process not the slabbing. Of course it is still unsightly and damaging to the coin. In conclusion the seed for corrosion was planted in the coin long before it was slabbed.

Sorry but i am a bit thick ,so may of missunderstood and if so apologise 🙂

IF....You mean that the cause of verdigris and corrosion are due to the metal mix in the blank and thiese would not happen if the blanks had been properly prepared ?

Then IMO i am not sure about  that ,yes the metals and mixes (blanks ) are sometimes more prone to verdigris GROWING on a coin such as copper but surely its not the only reason 😶

On the other subject........................

As far as people sending them for grading and them developing problems after

i feel your talking the odd one out of thousands and It is for the sender to check the coin before sending and the grading company to do the same and not start taking spots or bits off.

If its a cheap coin just take it out ,remove the verd and keep the ticket.If its an expensive one break it out and resubmit with the ticket.and if its been left to long then live with it but dont blame someone else ,as thats always the easiest option.

With regards the coin pictured it was purchased after (possibly well after ) the coin was slabbed ,so i doubt happened straight away and could of been years as a low UIN.If the coin was purchased in that state it should of been sent back if not happy the same as any other coin.If it was purchased at auction then like any other coin you take your chance if you dont view it in hand.

 

Edited by PWA 1967

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7 hours ago, ozjohn said:

Contamination is not the prime cause corrosion. For corrosion to take place cathodic and anodic sites must be present on the surface of the coin and the contamination aids the conduction of electricity between the two sites causing a chemical reaction and thus corrosion. In this case the Cu has not melted properly because of its higher melting point and along with Ag forms the other half of the corrosion cell with a potential of 0.28 v between them ( Cu. valency 1, cupric). If the alloy for the coin blanks had been properly prepared the corrosion would not take place despite the presence of contamination on the coin. Of course removing contamination from the coin's surface prior to slabbing would be a good idea and should be given some thought by TPGs. Given this verdigris is as a result of the manufacturing of the coin blanks prior to the minting process not the slabbing. Of course it is still unsightly and damaging to the coin. In conclusion the seed for corrosion was planted in the coin long before it was slabbed.

Say what? :wacko:

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On 5/6/2019 at 5:48 PM, Sword said:

I have brought a CGS slabbed 1937 proof crown from Lockdales using the CGS photos years ago. When I have got it, there's a carbon spot by the King's nose which is not visible in the CGS photo. The thought crossed my mind alright. 

I dont want to sound to harsh Sword but anyone buying at auction 😶

If your buying at auction and going off photos or a description and it turns up not as expected then whos fault is that.

Yes you can blame lockdales or anyother auctioneer but like any  coin if you dont look at them or ask someone else then its IMO our own fault.

I have bought a couple that i could not get rid of quickly enough and learned but like any auction its better to be sure what you may end up buying rather than any disappointment after.

Sometimes as i mentioned in another post its always easier to blame someone else and sure the seller was happy which is who the auctioneer was acting on behalf of.

 

Edited by PWA 1967

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37 minutes ago, PWA 1967 said:

I dont want to sound to harsh Sword but anyone buying at auction 😶

If your buying at auction and going off photos or a description and it turns up not as expected then whos fault is that.

Yes you can blame lockdales or anyother auctioneer but like any  coin if you dont look at them or ask someone else then its IMO our own fault.

I have bought a couple that i could not get rid of quickly enough and learned but like any auction its better to be sure what you may end up buying rather than any disappointment after.

Sometimes as i mentioned in another post its always easier to blame someone else and sure the seller was happy which is who the auctioneer was acting on behalf of.

 

Pete, I didn't blame Lockdales in my post. 

I merely implied that I strongly suspect the carbon spot was caused by mishandling when the the was slabbed. It has been problem free for ca 70 years and a spot developing after slabbing is too much of a coincidence. Mike expressed the same view with VickySilver's crown. Obviously, nothing can be 100% proven of course.

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