I just recently bought an 1886 s NGC graded MS64. I received it today in the mail, a d I was looking at it and there isn't a mint mark on the reverse. It was my understanding that "S" mints always had a mint mark. I looked at pics of the 1886 S online and it has a mint mark. But when I used my NGC iPhone app that scans the bar code the pictures it brings up of the coin show
no mint mark. I am confused. Any comments welcome. Thanks in advance.