Are all Costa sunglasses etched?
Are all Costa sunglasses etched? Whether you have glass or polycarbonate lenses, they will always have a “580” or “580P” etched into the lens. Lenses on real Costas will always have the 580 or 580P etched into the lens. How do you tell if glasses are glass or plastic? All you need to do is tap a lens against your teeth, a tool that's always available. If the lenses make a soft ringing sound, they are more likely to be glass. If they make a soft *thunk*, then they are definitely plastic. How can you tell if sunglasses are real?...