As with any collectible, sports jerseys also have separate markets: one for the authentic jerseys and one for the replicas. However, these markets aren’t distinctly marked any longer. They are now fused together, making it more and more difficult to determine whether or not a jersey is authentic. Furthermore, since there are several different types of jerseys and not every type is duplicated the same way, there are separate rules for each one. Learning how to tell if a jersey is authentic really isn’t difficult, but it takes quite a bit of time before you know exactly which questions to ask or which places to check even prior to your seeing of the actual product.
For all jerseys, take a look at the numbers and the patches. The numbers, if the jersey is authentic, should be sewn on. This applies to the entire number, not just the border. Also, some jerseys (example: 49ers) will have certain shadowing on the authentic ones. These numbers will have shadows to the right and under the number. Fake jerseys will have the same shadowing plus an extra black border around the rest of the number. These numbers that have shadowing all around are probably also screen printed. Jerseys that have sewn on numbers are more expensive to make. There’s a joke flying around saying that the more expensive your jersey, the more real it is.
Check for the patches on the jersey. Sometimes, you might have to match the player with their active years. There have been reports of a jersey with a patch that says he was active in 2000, when in fact he wasn’t. The anniversary patches all mean something different, and some replicators confuse one with another and slap on the wrong one.
Authentic jerseys have more vibrant colors than the fakes. However, this can become quite difficult to check for because replicas look quite decent when they aren’t directly compared to an authentic. If the color looks a bit flat, this should be a first red flag for you to proceed with caution.
If all else fails, check for the official logo of the NFL, NBA, or MLB. All official jerseys, no matter how good or bad they look, will carry the logo as a sign of authenticity. Usually the authentic jerseys originate from the respective official store anyways, so there’s no reason why the jersey shouldn’t have that logo.
It might seem easy, with only a few places to check, but you can also check for the inconsistency in material and a few other areas. Once you learn to appraise jerseys very quickly, your eyes can probably pick out the fakes from the real ones even if you don’t have the product, in situations like eBay.