Cheaper alternatives to a well-known sunglasses brand: what actually differs and what does not

Compared a lot of frames across price bands after getting annoyed at the numbers. What you are paying for is narrower than the price gap suggests, and wider than the cynical version claims.

Genuinely differs

• Hinges. The single most reliable predictor of how long a pair lasts. A proper metal hinge set into the material, rather than a pin pushed through plastic, is the difference between three years and one season.
• Frame material. Cellulose acetate, cut and polished, versus injection-moulded plastic. Acetate can be adjusted with heat by an optician, holds a fit, and does not go brittle. Moulded frames cannot be adjusted at all.
• Fit adjustability. Adjustable nose pads, and a frame a shop can tweak, matter more for comfort than anything else on this list.
• Lens quality at the edges. Cheap lenses are usually fine in the centre and distort toward the rim. Noticeable if you move your eyes rather than your head.

Does not differ as much as claimed

• Ultraviolet protection. Effectively universal now, including on inexpensive pairs. It is not the premium you are paying.
• Polarisation, which is cheap to add and widely available.
• The look, which is mostly shape and colour, and is copied within a season.

The practical split: spend on hinges, material and a shop that will fit them. Save on brand and on lens features that are standard anyway. And if you lose sunglasses regularly, buying cheap on purpose is a coherent strategy rather than a compromise, as long as they are actually filtering.