Adding to my collection

[AEATON-migration]

I got a new Mandela Currency for my collection last week. It's the prettiest of the lot and I tried to take a picture for the site - but I couldn't (what are you folks using?). This is minted in SA and has a face value of R25. 1oz Au, on the face of the coin, Mandela's profile looking ahead, in the background a side profile looking out of the bars of his prison cell, overhead the Union Buildings. This coin is the prettiest of the bunch. The fields are super-shiny, and the images are Matt. The coin celebrates 10yrs of a Democratic South Africa.

 

Here is a link of a site advertising it - though the picture doesn't do the coin justice AT ALL.

http://www.investgold.co.za/Protea_democracy.htm.

 

I find it strange that the fields appear to have ripples, as if it is a smelted coin, not struck - how would I know the difference? I want to know more about grading Proof coins. Where can I get some info?

[Hoot]

The way to tell the difference between a cast and a struck coin is that a struck coin will have a ring to it when struck on the edge, while the cast coin will have a dull thump. With a pair of cotton gloves on, balance the coin on your finger and strike the edge lightly with a pencil to perform this test.

 

Now, you don't need to do that with this coin - it's struck and in proof format.

 

The lines that you see are likely reflections of the area around you. However, these may be burnishing lines, which are very uncommon with proof coins struck with a close collar die, as are most (all?) modern proofs. Anyhow, burnishing lines occur due to uneven degrees of polish on a proof planchet before striking.

 

Hoot

[TomB]

I wasn't able to get the link you provided to work, therefore, I can't give a good explanation of what you are seeing. There are cases though of a halo effect, for lack of a better term, whereby the design elements of one side of a coin produce a shimmering effect in the fields of the other side. This is completely distinct from clashed dies. You may see this on high grade Barber coinage, particularly the half dollars, where the eagle's wings cause a halo on the obverse fields.

[AEATON-migration]

 

You may be tempted to say that these are scratches. They're definately not, the surface on this cion is the most perfect I've seen. Are they flow lines? They are not parallel, and kind of look like pouring - the way a drop of thin oil might run off a coin. I went to our mint recently and saw that they do use a polish on the blanc, which is then put through a process of cleaning to be removed before the coin is struck - I think it could be remnants of this polish ...

 

Collecting World Mandela Legal Tender

 

This one shows it better

[AEATON-migration]

Here you go:

 

 

[Hoot]

Perhaps die polish lines. Pretty awful quality control in a modern mint to find those on a modern proof.

 

Hoot

[HaydenTubbs]

still a very nice coin

[AEATON-migration]

Perhaps die polish lines. Pretty awful quality control in a modern mint to find those on a modern proof.

 

Hoot

 

The coin in hand has intense shine. Makes me contemplate if it was deliberately not put through the cleaning process / not properly cleaned.

 

Other coins from our mint do not have this - I find it strange. I shall look around for another example to compare !!