Sunglasses are a counterfeiter's ideal product: high margin, pocket sized, and bought on looks. Modern copies reproduce logos and frame shapes convincingly, which is why the giveaway has moved to the part that actually matters for your eyes, the lenses, where fakes cut costs invisibly.
A fake pair is worse than a cheap honest pair, because it darkens your view, prompting your pupils to dilate, while offering little of the ultraviolet protection the real lenses provide. This guide gives the checks that separate a genuine pair from a dressed up copy.
Hold the glasses at arm's length and look through one lens at a straight edge, a door frame or a line of tiles, then move the lens slowly up, down, and sideways. In a good lens the line stays straight. Ripples, bends, or a swimming effect mean the lens is optically poor, whatever the frame claims. Follow with the reflection check: genuine polarised lenses, where the model claims them, cut glare from a horizontal surface in a way you can test against a known polarised pair or the maker's test card sometimes included. Any straining, headache, or eye fatigue in the first wears is clinical evidence against the pair, not an adjustment period to push through.
Darkness is not protection. Tinted plastic without UV filtering can be worse than no glasses, letting more ultraviolet reach a dilated pupil. You cannot see UV performance, but it can be measured in seconds: many opticians and jewellers will test a pair with a UV meter, and reputable sellers of pre owned luxury goods do it routinely. Genuine luxury brands state the UV category and standards on the arm or accompanying card; vague phrasing like UV protection printed only on a removable sticker, with no standard referenced, is characteristic of copies. If the seller resists a test or the pair fails one, the conversation is over regardless of how good the frame looks.
Work the hinges: genuine hinges are smooth, firm, and often sprung, with tiny, neat screws or integrated mechanisms, while copies wobble, grind, or loosen within days. Read the inside arms for the full marking set: brand, model number, lens and bridge measurements, and country markings in the maker's usual format and font. Search the exact model number; if it does not exist, or exists in different colourways than yours, you have a finding. Cases and cloths are supporting evidence, since copies often ship with cases bearing slightly wrong logos or materials, but accessories can be swapped with genuine ones, so treat them as corroboration, never the verdict. Nose pads, lens seating, and overall weight all reward a side by side comparison with a genuine pair in a store.
Authorised opticians, the brand's stores, and established pre owned luxury platforms with authentication are the safe channels. Marketplaces are mixed: genuine resellers exist, but so do copy operations, and the price will usually hint which you are dealing with. A current season luxury model at a third of retail from a new seller is not a find. If checks reveal a fake, document the optical and marking evidence, claim through the platform or your card issuer as counterfeit goods, and do not wear them while the claim runs; your eyes are not a storage location. Then recycle the lesson into the group chat, because these sellers rely on each victim staying quietly embarrassed.
Not reliably. Simple home tricks are suggestive at best. An optician's UV meter gives a definitive reading in seconds, and many will test a pair free as a goodwill service.
Many have model and size codes printed inside the arm rather than unique serials. The check is whether those codes match a real model in the maker's range, in the correct font and format.
Yes. Counterfeit lenses commonly lack proper UV filtering and have poor optics. Dark tint without UV protection can increase the UV reaching your eyes compared with wearing nothing.
The straight line test: look through the lens at a straight edge and move it. Visible distortion or swimming means poor lenses, whatever the branding says, and it takes ten seconds.