1999-S clad state quarters...toning?

Does anyone else have the state quarter clad proofs toning on them?
Mine are graded (ICG) and are getting a target type of toning very similar to the 1974-S Ike's
Maybe its the plastic causing it? Whatever it is its toning quite a few of them.
Its hard to see. I will try to get better images.
I have a silver set in PCGS holders and no toning. Another one in the mint package and nothing
Stefanie
Mine are graded (ICG) and are getting a target type of toning very similar to the 1974-S Ike's
Maybe its the plastic causing it? Whatever it is its toning quite a few of them.
Its hard to see. I will try to get better images.
I have a silver set in PCGS holders and no toning. Another one in the mint package and nothing
Stefanie

CoinsAreFun Pictorials Album
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CoinsAreFun Toned Silver Eagle Proof Album
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Gallery Mint Museum, Ron Landis& Joe Rust, The beginnings of the Golden Dollar
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More CoinsAreFun Pictorials NGC
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CoinsAreFun Toned Silver Eagle Proof Album
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Gallery Mint Museum, Ron Landis& Joe Rust, The beginnings of the Golden Dollar
.
More CoinsAreFun Pictorials NGC
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Comments
Most of mine don't tone so my guess is they were exposed to something somewhere between minting and getting slabbed. Maybe they did not get rinsed well at the mint.