Quarter In 1975 Proof Set (Reverse Side) Not Silver Coated

to the Community!

50 years. I can't remember things from yesterday.

Dykil93,
I appreciate the response re oxidation at Mint. Wouldn't that affect BOTH sides of the coin? Font silver luster.

Also, is it considered an error coin if MINT was responsible for the abnormality?

I can understand some contaminant on the Reverse side that may have interacted and just affect that side. But, wouldn't that constitute an error at the Mint? Or doe a coin error specifically rule this out?

Thanks again. The images of the coin within its individual plastic case and within the plastic set case obvious can lead to any of the imperfections you described. Meaning imperfections in the plastic itself make the coin suspect of toning, as you describe it. If you could point out (use clock hands time) on the Comparisons or separate image areas you think indicate either toning or clad problems (please note which), I would appreciate it. I am unable to look at the outside edge of the coin because of the way it is packaged. We can only see the surfaces up to the edge. If you note on the Comparisons image, 3:00 shows the screw securing the inside separate case for the coin and thus the outer edge of the coin versus the beginning of the individual case. Looking at the coin edge I see only possible plastic imperfections (individual case or set case) and can't discern any actual coin imperfections other than the color which is solid and consistent across the entire Reverse surface. Is it likely that toning would be this consistent? Is it likely that toning of this nature came directly from the mint like this (I mentioned previously that the color has not changed since day one 48 years ago)? Is it likely that after 48 years the obverse is still not colored like the Reverse? What would a missing exterior clad look like (silver?) compared to the previous clad(color?). So far, the only conclusion I can come up with is the take it to a professional in its natural state to look at rather than to continue to take photos which have proved to present more problems than ever. What do you say? Given that, can you recommend someone in the Southern CA area with the solid experience to assess this set? Thanks.

More about Proof Error Clads:
The following articles explain the clad layers and errors that can occur at the mint. There are definitively proof mint coins that are designated as either Obverse-Missing-Clad-Layer or Reverse-Missing-Clad Error or both as described in the first article below:

https://www.pcgs.com/news/missing-c...lar%20coins.

https://nnp.wustl.edu/library/dicti...ped%20letter.

Note: Some images of missing clad coins are in the first article.

I am no longer interested in responses related to the photos submitted by me or others. Imperfections in the separate plastic case and set case prevent showing the natural set compared to the native eye.

I only seek whether anybody has ever reported/posted or seen a Reverse-Missing-Clad-Layer quarter in a 1975 Proof Set other than me.

Buy another set and weigh them both to compare or open the case and weigh it. Each side clad layer weighs a full gram.

Here's one for 8 bucks.
https://www.ebay.com/itm/326386907449

If you weight them, then get a scale that does two 0's after the decimal, example(5.67 grams). Or make a basic scale with two coins and put both coins on the same piece of wood and balance them. If you can't balance them at the same position then one is obviously heavy than the other, obviously scale is better though. Just a quick comparison option.