How can you tell a real Perlina handbag from a counterfeit one?

Perlina handbags are not a huge counterfeit item, so the worry of getting a fake one is less. If you get it through a reliable outlet, like a real store and not online you are safe. Otherwise look closely at the stitching. Fakes will tend to not have as good / as clean stitching, especially inside where it is less obvious.