How to distinguish? [solved]

So, I *think* I fooled myself and accidentally ordered the N# 28046 (CuNi) thinking it was it's twin N# 347749 (925 Silver). The offer didn't specify, but only showed pictures. I didn't know there was a twin coin with the same diameter and weight, so now it seems more likely I didn't get silver.

I then reached out to someone else selling the silver version, and he confirmed there are no coin marks indicating silver. As far as I can find, the coins are identical, except the silver one is Proof. And according to Ucoin, the silver one also is thicker.

But that last part makes no sense at all to me. Silver is more dense, so given the same diameter and weight, the silver coin should be thinner, not thicker.

Can anyone help shed some light on this?

Numista doesn't have a thickness for the silver one. Probably the thickness in Ucoin is user input so not reliable.  Regardless, the thickness of a coin should be the thickness of the rim not the thickness of the interior of the coin. What did Ucoin have for the thickness?

Ucoin lists silver as 28,28 g 38,8 mm 3,3 mm

And it lists CuNi as 28,47 g 38,8 mm 3,1 mm

Numista's silver is 28.28 g 38.6 mm no thickness

Numista's CuNi is 28.35 g 38.61 mm 3 mm

Either the coin specs are wrong, or I just don't understand.

I wouldn't put too much stock in those thicknesses.  Also, a thicker rim doesn't mean the field and details are thicker. Coins are not a cylinder.   

It came in today. I measure:

weight: 28.3-28.4 g

diameter 38.5-38.6 mm

width: 3.1-3.2 mm

But I have no idea to tell if this is the proof version or not. The sender actually taped the coin to some cardboard without protection, so there's some tape residue on the coin's face. Maybe I should give it an acetone bath?

Can someone help me identify whether this is the proof version or not?

See the video here:

https://youtu.be/QOieiAGneJc?si=WPZgxC2Dtdk_3t5y

Adding two more photos to show surface.

MooiZilver

It came in today. I measure:

weight: 28.3-28.4 g

diameter 38.5-38.6 mm

width: 3.1-3.2 mm

 

But I have no idea to tell if this is the proof version or not. The sender actually taped the coin to some cardboard without protection, so there's some tape residue on the coin's face. Maybe I should give it an acetone bath?

 

Can someone help me identify whether this is the proof version or not?

 

See the video here:

 

https://youtu.be/QOieiAGneJc?si=WPZgxC2Dtdk_3t5y

 

 

If you mean Proof being the silver version of the coin, then no, it looks like (and as you have already stated) a Copper Nickel coin. Standard uncirculated version not a Proof.

King

If you mean Proof being the silver version of the coin, then no, it looks like (and as you have already stated) a Copper Nickel coin. Standard uncirculated version not a Proof.

Thanks. Appreciated!

If you don't mind me asking, what tells it isn't proof? I would like to know the difference.

Seen as you can even see the reflections of the 2d barcode, I was doubting.

Also, I have here a proof Marshall Islands $50 which has more or less the same surface structure.

So just trying to learn here, not to debate.

A simple way to determine if it's silver or Cu-Ni is to do the ice cube test.  Use a control coin of known silver composition of similar diameter and weight such as N#13324.  Put ice cubes (same size) on each coin. Notice the speed of melting. If the ice cube on the control silver coin melts faster than the other then it is not silver.

I mean for starters, this coin wasn’t minted in Proof according to the page, it says that the silver version is proof, but that might also be a standard strike looking at the images on the Numista page. But if the producers of the coin say it is proof, who am I to argue.

If you have a business strike and a proof version, the first thing to do is see if there is a pretty case or box and paperwork with the coin, saying its a proof (the majority come like that), if for some reason the proof coin has been removed from this and found its way raw onto the market, it is best to compare 2 or more versions. However generally a modern proof will have mirror finishes in the fields and frosted surfaces on the details, or as near as possible to that. Mostly the finish is far higher quality than normal coins. A good set to learn from are the Austrian shillings 25 & 50 denominations, they have normal and proof, cost not so much over silver (though now is not best time to buy because silver price too high) and are easily available to buy on eBay etc. Often the proofs are raw and the distinction between the two is pretty obvious.

Hope this helps, but until you have many certificated proofs and experience there of, assume everything you find or buy isn’t a proof.

MooiZilver

King

If you mean Proof being the silver version of the coin, then no, it looks like (and as you have already stated) a Copper Nickel coin. Standard uncirculated version not a Proof.

Thanks. Appreciated!

If you don't mind me asking, what tells it isn't proof? I would like to know the difference.

Seen as you can even see the reflections of the 2d barcode, I was doubting.

Also, I have here a proof Marshall Islands $50 which has more or less the same surface structure.

So just trying to learn here, not to debate.

Visually? here: https://www.youtube.com/watch?v=GFv2995KBPI
 

King

I mean for starters, this coin wasn’t minted in Proof according to the page, it says that the silver version is proof, but that might also be a standard strike looking at the images on the Numista page. But if the producers of the coin say it is proof, who am I to argue.

 

 

Yes, the reverse photo of the SIlver Proof on the Numista page shows either coin wear or die wear, neither of which we would expect for a modern proof. 

I agree with both comments that this coin could be a proof, or just a very high quality circulation strike.  I like rsirian1's suggestion.

So, I'll need to get me some ice cubes :). Will look tomorrow.

For now, I'm still wondering about the thickness. Silver should be at 0.4+ mm (13.8%) thinner, given same diameter and weight. I concur with Ucoin probably being incorrect. (And Numista too!)

I probably didn't explain it well enough.  The thickness is that of the rim which is larger than the field/details of the coin. Assuming your measurements are correct (for your coin, not necessarily the entire population of coins) then with the silver having a larger rim it could have a smaller field/detail thickness to keep the weight the same as the Cu-Ni coin. That's the typical way they keep the same weight for different compositions.  Schematically this can be shown in this sketch of the cross section of the coins.

MooiZilver

So, I'll need to get me some ice cubes :). Will look tomorrow.

 

For now, I'm still wondering about the thickness. Silver should be at 0.4+ mm (13.8%) thinner, given same diameter and weight. I concur with Ucoin probably being incorrect. (And Numista too!)

Here, to know if it's silver, and how much silver it has:.

http://www.attilacoins.com/Calculate_Specific_Gravidity_coin.asp

juliofcampos

Here, to know if it's silver, and how much silver it has:.

http://www.attilacoins.com/Calculate_Specific_Gravidity_coin.asp

 

I actually created a 3d print of this :) But it broke during transport a while back, so I need to print a new one. (will take 12 hours of printing).

MooiZilver

juliofcampos

Here, to know if it's silver, and how much silver it has:.

http://www.attilacoins.com/Calculate_Specific_Gravidity_coin.asp

 

I actually created a 3d print of this :) But it broke during transport a while back, so I need to print a new one. (will take 12 hours of printing).

This might be more your style: https://en.numista.com/numisdoc/determining-the-metal-of-a-coin-27.html

We can lay this thread to rest.

I used two coins to test. This Gibraltar coin and a known .925 (sterling) coin N# 13306.

First I tried with the magnet slide test (Eddy currents) and both showed similar deceleration, bringing my hopes up for silver. But I already know that copper also has significant Eddy currents features, and the coins are not similar in weight/size.

I didn't bother printing out my 3d water disperse bridge, but used some some thread to hang the coin in water on a scale, as also was recommended.

It's not a perfect/expensive scale, but the results seem accurate enough.

- the sterling coin came as back as ± .950 silver.

- and the Gibraltar coin as ± .950 copper, so they even skimped on the nickel.

So, even though it has a near proof appearance, it's indeed not the proof variant that is silver.

If anyone does have the silver one, please confirm specs.

Very good.  Just an fyi…Cu-Ni does not react to magnetic slides like copper does so I'm not sure what was going on there.  Here's 4 screen shots from a video I made of a 800 Ag vs. Cu-Ni on a magnetic slide.

And the complete video.

Put your slide at a lower angle and try both a copper and a silver coin. You should notice the affected acceleration with both coins. I use an angle that is just enough to guarantee a slide down, but with the least amount of acceleration. That way you can more clearly see it when it passes the magnet.

In my test however, the silver coin was under 18 g while the cuni coin was over 28 g. So that's one factor. Also, as I found out, the cuni coin was ± 95% copper, so more copper than your regular 75-25% ratio. That's another factor. Copper, like silver, is very conductive, and does show Eddy currents features.

Also, good to know, I've seen cuni coins that were mildly picked up by magnets, and some (like this Gibraltar one) not at all. I believe that has to do with the copper nickel ratio, as nickel is ferro-magnetic.

If the angle is too small then sliding friction tends to dominate.

Nickel is ferromagnetic. Typical Cu-Ni like 70/30 is not.  95/5 Cu/Ni does react like copper. What is the composition of the Gibraltar coin?

Pure aluminum goes down the slide even slower than silver or copper but with just a few percent magnesium it goes down very fast.

I have a cheap scale. Not precize enough to give an exact composition, but enough to say it's no 70/30%, probably more like 90/10% or even 95/5%.

Unfortunately the Pobjoy Mint stopped their activities. There's still a website but all the specific information about their coins is gone there now. But as far as I can remember Pobjoy Mint never struck copper-nickel coins in proof. Although I have to admit the quality of their coins was often so well I can imagine you start doubting if they were proofs or not.

But there's another aspect you don't mention. What did you pay for the coin? The bullion value of the silver proof is 57 €. The price for the copper-nickel coin is around 10 €. So normally the price should already be a perfect indicator of what you have.

I like the tissue test. Here are two identical coins, on the left the copper-nickel version, on the right the silver version. You can clearly see the difference:

MooiZilver

I have a cheap scale. Not precize enough to give an exact composition, but enough to say it's no 70/30%, probably more like 90/10% or even 95/5%.

If I am not mistaken, it's unlikely this test can tell the difference between those compositions, which differ by only 0.05 in specific gravity (or density).  Especially if the scale is not that accurate.

But it can tell the difference between sterling and cupronickel.

tdziemia

MooiZilver

I have a cheap scale. Not precize enough to give an exact composition, but enough to say it's no 70/30%, probably more like 90/10% or even 95/5%.

If I am not mistaken, it's unlikely this test can tell the difference between those compositions, which differ by only 0.05 in specific gravity (or density).  Especially if the scale is not that accurate.

But it can tell the difference between sterling and cupronickel.

I just double checked, and you are right.

Essor Prof

Unfortunately the Pobjoy Mint stopped their activities. There's still a website but all the specific information about their coins is gone there now. But as far as I can remember Pobjoy Mint never struck copper-nickel coins in proof. Although I have to admit the quality of their coins was often so well I can imagine you start doubting if they were proofs or not.

 

But there's another aspect you don't mention. What did you pay for the coin? The bullion value of the silver proof is 57 €. The price for the copper-nickel coin is around 10 €. So normally the price should already be a perfect indicator of what you have.

 

I like the tissue test. Here are two identical coins, on the left the copper-nickel version, on the right the silver version. You can clearly see the difference:

 

Pobjoy issued CuNi coins in standard finish and sometimes also as Diamond Finish which is something superior to standard, with mirror like effect but no so intensive as proof. 

Anyway, tissue test is simple and very useful. Silver coins are much brighter than CuNi.

MMowiec 

Pobjoy issued CuNi coins in standard finish and sometimes also as Diamond Finish which is something superior to standard, with mirror like effect but no so intensive as proof. 

That's true. Like this ones: https://en.numista.com/catalogue/index.php?r=tonga+50+car&st=1-2-3-47-155-156&cat=y&im1=&im2=&ru=&ie=&no=&v=&cu=&a=&dg=&i=&b=&m=&f=&t=&t2=&w=&mt=&u=&c=&wi=&sw=