It's a coin toss. The only way to tell is to look at the coin under a 5x or more. But since I can't, let me start by asking what the grade of the coin is. Given that you know the grade, then you must inspect the coin. If the actual preservation does not conform to the grade I would say it's AT. Why? Because one of the main reasons for AT is to cover up marks on the coin. Some people will buy a toned coin only using the naked eye as the determining factor. Sad but true. There are many more factors to determining AT vs. NT. But this is a start.
I do not intentionally collect toned coins. I just don't particularly care for them. But I do read. If I understand correctly, a coin naturally toned like that most likely came from one of two places: 1. A roll of silver dollars with that one being an end coin. But if that's the case, then the other side would NOT look the same. 2. A coin album of the type with plastic sliders on both sides. In this case both sides could easily resemble each other. Please poke holes in and/or add to my analysis. That way I'll continue learning.
I would guess both. The toning around the center looks AT, while the edges look like they're just beginning to tone naturally. Either way, nice colors...not too overboard. Guy~
Always hard to tell from a photo, but it looks similar to some album-toned pieces I have that I know to be genuine. Some of the older albums used paper that produced very nice toning. On the down side, these pieces frequently have fingerprints from someone pushing the coin into the slot. Dan
kanga: Also, coins that were kept in the original mint canvas bags did a nice toning job. Plus the sun, and those old brown coin envelopes. The best were the old Wayte Raymond albums, lots of sulphur.
Looks NT, but could also have been "helped". I've seen (what I would consider) NT and AT examples with this type of toning. Would need to see in hand to be more sure (and to look for patina)...Mike
The mint bags generally only resulted in toning on one side, like coin rolls. Don't know about the sun. Those old brown coin envelopes were REAL nasty. Leave a coin in too long and you ended up with a black disk. I messed up a couple nice 1000 yen Japanese coins from the 1964 olympics that way. And of course the old albums. Many of my UNC 1941-1964 quarters suffer from some unsightly toning because of album storage. I'd be interested to know what the TPGs use as keys for detecting AT.
So what's 'too' long? You're saying if I take a nice BU silver coin & put it in one of those brown envelopes... it will tone like the one in this thread?? In a drawer? Where? How long? (I want to experiment and try but not end up with a black disk)
That's easy, experience. You need to keep in mind though, they don't really care if it's AT or NT and they will slab both - provided it is "market acceptable".