[PJ]

You can just tell by the quality of everything. Box, cloth, authenticity card, the glasses itself.. The materials on fakes feel VERY cheap. Super light and brittle plastic, flimsy metal.. Also the joints. Fakes will feel loose and flimsy. Real pairs are super solid and sturdy.. after all, retail is like 3, 4, 500+.

I think with those reputable places you'd be pretty safe, as they've been around a long time.. so you don't really have to worry. Fake sunglasses are pretty obvious.. if stores were selling them, they'd be shut down rather quickly..