Toning Like A Ticking Clock...

The lighting and processing are different between the two. The main difference in toning is that the metallic blue color is creeping in from the edges, and it's also developed some dark spots.

I've had silver coins tone in holders, and some even develop ugly dark spotting. One of them PCGS did their magic and removed the spots and re-holdered.

It's undeniable that coin has toned further in the slab. But it's also a major concern.

I've heard of Indian cents changing from red to brown which severely impacts the value of the coin. But this is the first silver example I've seen that has changed in the holder.

One of the benefits of storing coins in a TPG holder is the assumption that the coin will be preserved in its present form and will be protected from the elements. So when you see toning changes like this happen inside of a TPG holder it's a bit unnerving.

Do you guys think an acetone bath before the submission would have stopped the toning progression?

Fortunately, this isn't a particularly pricey coin, so I'm not too bothered. So far it's gotten better. But I expect in 15 years or less, it'll be turning black.

TPG holders are not air-tight, nor are air-tites. Plastic simply isn't a barrier to gasses. Some is better than others (mylar would have better archival properties, and metalized mylar better still).

You could store coins in a vault under a vacuum in extreme cold to slow chemical reactions as much as possible, or you have them on your shelf and enjoy them.

The lighting really isn't all that different. Same camera, same lighting diffusers, same lights (jansjos), just a bit more light from the bottom and somewhat different exposure settings. You can also look at the photos from the original HA sale. There was only blue on the rim and, not all over the cap and the field.

I'd crack it out and rinse it in acetone. That should stop the oxidation. Then put it in a Mylar flip and it should not change for many years.