MS-64 and I love the toning.
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That is natural looking pull away toning. Somoething to do with strike hardening and how the surfaces react after but I'm not exactly sure how it forms.
Good question, and hard to give a definitive answer. I believe that it is caused by the amount of metal flow from the rims in when the coin is struck. This is the area of greatest metal movement as the metal is pushed from the rims inwards to the point the relief begins (the stars and date). This surface area then becomes more resistant to toning.
This explanation however does not explain why we only see it on certain dates and mintmarks. It has been proposed that during times of poor quality control at the specific mint, where the dies may not have been cleaned as often, the corresponding grease build up and subsequent transferral to the surface may play a role as well.
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Posted 10/13/2018 12:14 pm
