You’ll want to look for things like if the edges are more compressed the closer to the corners you get. Also, if you sheen the card under a light source, there can be differences in the gloss as you get near the corners or some instances of white spotting. Post a pic when you can. Here’s a topps gretzky I have that was in a screwdown and I bought in a PSA authentic altered holder.
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Trading! See my Flickr "For Trade" album (updated Dec 2023) as well as an album of my PC stuff.
https://www.flickr.com/photos/197267578@N07/albums
If you want a card, you might not get a deal. If you want a deal, you might not get a card.