Toning on 1972 nicaraguan proof set.

Redfox

Hi,

I have recently bought a 1972 nicaraguan proof set. Although it isn't particulary rare (about 20 000 pieces), it is hard to find it for sale. The coins are made out of copper-nickel. My question concerns toning. As it can be seen on photos below, all the coins are toned on the obverse. As far as I know the alloy does not tone easily, so that I am concerned that it may be artificial.

Also, there's some kind of tarnish (?), on a 10 centavos reverse. I have marked it with a red circle. Does anybody have idea what it may be?

Thanks for help,

Redfox

P.S. These are the photos from a seller. I haven't received the set yet.

thefinn

Real toning. Nickel doesn’t tarnish easily, but cupro-nickel will, especially under the right conditions.

pruebas

In the early 70s, PVC was a common case material. Maybe toning/damage from off-gassing?

Redfox

I would venture to say that it is not any kind of pvc damage.

Here, a photo of a case for the set (from another auction, but mine will also come
in such a box):

pruebas

@Redfox said:
I would venture to say that it is not any kind of pvc damage.

Here, a photo of a case for the set (from another auction, but mine will also come
in such a box):

I wouldn't be too sure. Maybe not PVC, but these cases often have open-cell foam and glues that off-gas and cause issues. I have seen it many times.

More recently, the Royal Mint includes anti-tarnish paper with their cased coins partly for this reason.

Nice set, BTW!

Redfox

Thx @pruebas. I have been captivated by the sun motive ever since I had seen it a few years ago.

291fifth

The coins are 49 years old. Who knows where or how they have been stored for all those years. The toning is probably natural.

7Jaguars

I vote natural toning as well. Occasionally there is some even more vivid toning than this on such issues. The toning spots are sometimes termed "flyspecks" when they are likely an early stage of corrosion/oxidation.