a gem mint grade is incredibly difficult. not only is the condition of all the corners, etc. highly scrutinised, but the surface is also looked at very closely as is the centering of the card. most of the cards made back in the day are very seldom perfectly centered. even now it is not always the case. it also depends on what grading company awards the grade.
I am not sure what that guy was talking about, but this is a MJ rookie with an incredibly tough grade.
http://www.ebay.com/itm/1986-87-Fle...82935920?pt=US_Basketball&hash=item4177cf1b70
you will very seldom see a card graded higher than BGS 9.5
they do award 10's occasionally but it is by far the toughest grade to attain. a BGS 10 and a 10 from another company like PSA are not the same.
a BGS 9.5 is incredibly good for that card.
http://www.ebay.com/itm/1986-Fleer-...69031303?pt=US_Basketball&hash=item51b16c8987
this is the MJ rookie with a PSA 10, which is also a very good grade. PSA 10 and BGS 9.5 are typically seen as the same, but obviously a 10 on an older card is a bit different.
there is a reason this card would have been sent to PSA and not BGS.
this is about as good as it gets for an MJ rookie. I imagine if there is one out there, a BGS 10 would sell for slightly more but couldnt see it topping 20k.
am thinking perhaps the guy meant 10k and not 100k.
either way, you made a great investment at 500 bucks. whenever you do decide to sell, it would probably behoove you to take a good look at the MJ and maybe get it graded because it could be the difference between hundreds and thousands of dollars.