A new arrival and a new (for me) method of guessing the grade: using the NGC Photo Vision. Please add any comments along with guessing in the poll.
The obverse has me confused. Looks like surface damage. Otherwise, seems like lots of luster on the coin.
I'll add a video that people can take a look at (use arrows on side to scroll to reverse): https://www.instagram.com/p/B4863YDgOFC/ It's not a details coin (and thus I didn't add that option). The coin does have semi-prooflike surfaces (stronger on reverse), which isn't always easy to capture in a photo. It is also a fairly small coin (around the size of a US Dime).
Spanish Colonial coins, like this Mexico City mint 1/2 real often come weakly struck so that what may look like a vf/xf-type wear coin is actually uncirculated. In this case I think high AU if not MS. More likely MS-something if one looks at the edge devices which appear unworn. Probably dipped, but not harshly cleaned, so not details. MS-63 is as close as I can call it.
Maybe the third time I say it will be the charm: it's not a details coin! There are no hairlines; there is no corrosion. A dip is possible (as is the case with any untoned coin that is this old. While the guess the grade is for the current iteration, it is interesting to note that this coin was graded twice and straight graded both times (once at PCGS and once at NGC).
The surfaces and appearance of that coin are like nothing I’ve ever seen before. I say MS63 just because it’s pretty clean.
Could it be from a die that had rusted, and the fields were later polished? Voting 64 because I have no reputation to lose and because so little of what’s going on looks post-mint.
The answer is MS 62. The coin also came with an old green label, graded MS 63 by PCGS. The seller told me he had cracked it and sent it to NGC hoping for an upgrade (or at least the same grade). Looking at it, I see where he was coming from and believe 62 is a bit low. I could definitely see it as a 63.
What's interesting is that I can barely see anything in hand (the picture really blows up the coin). I'm not sure what happened; it might be what @xlrcable suggested above (rusted die).