Blue/green colour toning on gold sovereign

[Booky586]

I have a 1965 Gillick Head Elizabeth II gold sovereign which looks like it's a slightly different colour to my others, but never thought too much about it. Now I've started to take photos of coins for my records and this one looks like it has a greenish blue toning on it, more apparently on the reverse. Is this normal or could it be a contamination from a plastic flip cover or capsule? I've never seen rich toning on a gold coin before.

Any ideas or thoughts appreciated, coin photos below:

[Coolsmp]

Are you sure its actually gold?

[Booky586]

Yes, as sure as I can be. It's size and weight are to specification and the design, by comparison to other Gillick heads, is the same.

[Midasfrog]

Where did you buy it from ebay ? I would check it with a tester if you know someone close who has one. Gold dosnt tarnish even after being buried in the ground for hundreds of years. 

[dicker]

Hi All

I agree this is a bit odd but the coin looks ok to me in terms of the features.  Photos are always very difficult to assess In Terms of colour.  
 

So assuming that this is the genuine article, why might this have happened?

Don’t forget that a Sovereign is not pure gold and I think that QE2 ones were formed from Copper and Gold but no silver.

It is possible that the copper component may have oxidised or reacted with another chemical and or have been heated   (Example Sulphur)?  

I am not a chemist nor have I seen a coin like this before so just my guess.

Will be interesting to see what other forum members think  

Best

Dicker

 

[Arganto]

Got to be oxidisation of the copper, unless they snuck some nickel in there 😁

Could be sulphur doing the dirty, or some other chemical in the local environment where it is/was stored. 

Nice camera work by the way OP 

[Booky586]

22 hours ago, Midasfrog said:

Where did you buy it from ebay ?

It came from a reputable bullion dealer, in a plastic wallet. I've recently put it in a air-tite capsule.

 

2 hours ago, Liam84 said:

Got to be oxidisation of the copper, unless they snuck some nickel in there 😁

Could be sulphur doing the dirty, or some other chemical in the local environment where it is/was stored. 

6 hours ago, dicker said:

Don’t forget that a Sovereign is not pure gold and I think that QE2 ones were formed from Copper and Gold but no silver.

It is possible that the copper component may have oxidised or reacted with another chemical and or have been heated   (Example Sulphur)?  

Yes, I tend to agree, It was just that I had never seen blueish toning on a sovereign. I have older ones, but all of them look very clean, so I was suprised to see it on a relatively newish coin.

It's definitely a keeper, at first I thought I would clean it but it's started to grow on me the more I see it!

 

[Arganto]

It's got a bit of character and wears it's patina well. Is that picture representative of what the coin looks like 'to the eye' under normal lighting? I only ask as the colour looks a little washed out, I suspect it appears more golden in hand? The young head Elizabeth coins are very nice indeed. 

[Prophecy]

Is that not the patina of a coin stored in a crappy plastic wrapper?

[Booky586]

On 27/05/2020 at 23:35, Liam84 said:

It's got a bit of character and wears it's patina well. Is that picture representative of what the coin looks like 'to the eye' under normal lighting? I only ask as the colour looks a little washed out, I suspect it appears more golden in hand? The young head Elizabeth coins are very nice indeed. 

Yes, under natural lighting the coin looks more golden as you would expect. The loss of colour in the photos is down to the limitations in my skills and equipment.

I agree with you about the Gillick head Elizabethan sovereigns. They have the quality and old world appearance of the Victoria\Edward\George coins that you just don't get with the new bullion sovereigns. And they can be had for bullion prices in good grades too.

[Booky586]

1 hour ago, Prophecy said:

Is that not the patina of a coin stored in a crappy plastic wrapper?

It could be.

It's there anyone out there stored there sovereigns in plastic wallets and had a similar reaction?

[dicker]

1 minute ago, Booky586 said:

It could be.

It's there anyone out there stored there sovereigns in plastic wallets and had a similar reaction?

I purchased some Gillick's that had been stored in vinyl flips (seemingly) from early in their life and they are all in great shape apart from a 1968, which just appears a bit dirty (not tarnished).

Best

Dicker

[Prophecy]

https://www.thesprucecrafts.com/pvc-damage-on-coins-768300

It could be something like this; it does have a blueish tinge (although blue is usually an indicator of reactive silver rather than gold)

[Booky586]

33 minutes ago, Prophecy said:

https://www.thesprucecrafts.com/pvc-damage-on-coins-768300

It could be something like this; it does have a blueish tinge (although blue is usually an indicator of reactive silver rather than gold)

Hmm, I'm pleased you've highlighted this, but I'm not convinced my coin is showing the problem that's happening to the coin in the link. That has corrosion on the high surface points of the coin, where the pvc sleeve has been in contact, whereas mine has tarnish in the field and not on the high points.

[Prophecy]

It actually looks like grubby coin fingers have fondled it a lot over its life.

[Britannia47]

If the photos are a genuine representation of the colour as seen by the human eye, then they are more than a  'slightly' different colour. In fact I am surprised that you even bought it from your 'reputable' bullion dealer if it looked like that.  I have never seen a sovereign that colour in 23 years of collecting sovereigns. As stated by others, gold does not tarnish in that way, even after sovereigns were  recovered from a shipwreck after 132 years (Steam ship 'Central America') they were as good as when minted. I know nothing about PVC, but suspect the main culprit might be the alloy. The colour reminds me of the post 1947 'silver' coinage - half crowns etc which used copper-nickel. Nickel used as an alloy will bleach just about anything. The coin certainly looks genuine however and in great condition. I recently had an 2005 'Australia' sovereign tested because of its unusual colour and found out the alloy was all silver- no copper at all! You might consider having your coin tested to help solve the mystery.

Good-luck.