How to know if an unsigned card is a reprint?

[drcy]

If you have cards from the same issue, the reprints should be pretty obvious in multiple ways-- thickness, cardstock, gloss, opacity (see-through effect when the card is held up to a light), etc. In fact, if you handle a lot the cards, reprints will usually be obvious just be the general look.

So, if you're collecting Topps, it would be a good idea to get an assortment of commons from the various years for comparison.

But, in general, old Topps have genuine slightly rough cardboard backs and edges-- dark grey to lighter in color. They put a smooth surface on the front of the cards before printing the fronts of the cards, so the fronts are smoother and a bit glossier than the backs. After you get few Topps from any years, you will see this. Topps cards from the 1950s to 80s are all like this.