Well, if you have already bought Persol sunglasses, and you wanna know its authenticity, you gotta figure out several questions. Firstly, where did you buy them, in a big shopping mall, or just online? Sometimes, online shopping is not safe, for some sellers sell fake ones through the Internet. Then, you should contact the after sales service to see if they are real or fake, they will tell you the most useful way. So, you should make sure everything is safe before you make a deal.
The feeling of wearing the real Persol sunglasses is so comfortable. You should at first try it on and have the feeling. If they are fake, you must feel not perfect. Then you can see the brand printed on the sunglasses flame sides. It should be printed smoothly, with no flaw. Lastly, observing the detailed parts, you will know whether it is true or false.