If you want to spot the fake porsche sunglasses, the easy way is to bring the sunglasses to the real store and ask the client. Usually the franchise store will sell the real ones. You could also check it by yourself from the brand mark point, the detailed manual workmanship and other aspects. You could also wear it to feel the real feeling. If it is fake, it will not be comfortable.
As far as I know, porsche sunglasses are one of the most luxurious designer sunglasses in the world. And of course many dishonest dealers are selling fake ones. However, there are many ways to tackle this problem. So, before you do the deal, you should carefully check the quality, then ask for warrenty. Usually , there will be something called serial number on the sunglasses which is designed to tell its authenticity. Check it and call the hotline to see if your sunglasses are authentic.