The hobby of Card Collecting is made up of a community of kind people, willing to help you complete sets, build your personal collection and share information. But as is often the case, there can be a few people who try to take advantage of other's kindness. Sometimes they will even go so far as to alter or produce fake cards for profit.
One method that is used involves jersey cards, sometimes using a base card, imbedding a fake jersey swatch onto it and sometimes replacing a one color jersey swatch with a fake multi-colored patch in hopes of increasing the cards value.
Fortunately, Panini puts an authentication identifier on their Jersey Pieces to ensure the piece of memorabilia on the card is real. But identifiers can not be seen just by looking at the card.
Here is a quick video tip with one method to see if the Panini jersey piece you have is a real.
Direct Link to the Video
This is not the only method. Panini also provides an authentication service that uses the KODAK Traceless System for Anticounterfeiting. If you have any doubts, use this link to have your card checked out.