Yesterday I scanned this Silver Eagle in preparation for selling. I was amazed when I saw the area around the circumference of the obverse. I had not noticed this before. Is this "toning" or something else? Does it affect the grade of the coin? Is it caused by poor packaging by PCGS? The reverse of the coin seems to be fine. Thanks for any opinions!
Yes, it is a form of corrosion/toning and significantly affects value. If you sent it into PCGS yourself, you should have rinsed the coin in acetone before hand, as the initial damage was probably much , much less then. No holder is air-tight, not even Air-Tite(tm), so its up to the owner to maintain the coin afterwards.
It is referred to as "milk spotting." It is not fixable, and is permanent. It often appears years after slabbing, and will significantly adversely affect the grade and value. The coin is now worth its silver content, and only its silver content. To be fair, I'm sure it was probably blast white and perfectly attractive when PCGS originally slabbed it. It is common for these to turn after slabbing.
