Two pairs of sunglasses can look identical and behave completely differently once you step outside. The difference is in the lens. Here is what each term on a lens tag means, which ones matter for your eyes, and which ones are simply a question of style.
UV protection: the only non-negotiable
Ultraviolet light is what damages the eye over time, and it has nothing to do with how dark a lens is. A very dark lens without UV filtering is worse than no sunglasses at all: your pupil opens wider behind the tint and lets more UV in. What you want is UV400 (sometimes written "100% UV" or "UVA/UVB"): the lens blocks all ultraviolet light up to 400 nanometres. The designer brands we carry build their lenses to this standard; if you have a doubt about a specific model, ask us before you order.
Lens category: how dark is dark
European lenses carry a category from 0 to 4 that describes how much visible light they let through:
- Category 0–1: clear to light tint. Fashion and low light. Think of the pale pink or yellow lenses on some Gentle Monster and Balenciaga models.
- Category 2: medium tint, for cloudy and mixed weather. Most gradient and lightly tinted lenses.
- Category 3: dark tint, for bright sun. The standard for everyday sunglasses, and what most of our catalogue is.
- Category 4: very dark, for high mountain and open sea. Not allowed for driving.
Polarized: for glare, not for UV
A polarized lens has a filter that cuts horizontal reflected light: the glare off water, wet roads, a car bonnet or snow. It makes a huge difference when you drive, sail or spend the day at the beach, and it reduces eye fatigue. Two things to know: polarization is not UV protection (a lens can be either, both or neither), and polarized lenses can make some phone and car screens look dark at certain angles. If you mostly wear sunglasses in the city, you can live without it; if you drive a lot, it is worth it.
Gradient: style with a practical side
Gradient lenses are dark at the top and lighter at the bottom. The top shields your eyes from the sun, the lighter bottom lets you read a menu or a dashboard without taking them off. They are the signature of aviators and many oversized shapes, and they flatter the face because they do not hide the eyes completely.
Bottega Veneta Aviator Sunglasses
The aviator is the natural home of the gradient lens: dark on top, lighter below.
Dior 30Montaigne S7U Sunglasses
On a cat-eye, a lighter lens keeps the eyes visible and the look soft.
Mirrored: the look, plus a little extra
A mirror coating reflects part of the light before it reaches the lens, which makes a mirrored lens slightly more comfortable in very bright conditions. Mostly, though, it is a style choice: silver, gold, blue or pink mirrors hide the eyes completely and give a sporty or futuristic look. Mirror coatings scratch more easily than plain lenses, so keep them in their case.
Unisex Square Blue/Silver Sunglasses - Gentle Monster Dust Musk BL9
Square metal frame with a blue tint: the kind of lens that is chosen for the look.
Men's Wraparound Black Sunglasses - Gentle Monster Turbo MG21
Wraparound shape: the sport-inspired silhouette that pairs best with dark or mirrored lenses.
Tinted and coloured lenses
Grey keeps colours true and is the most neutral choice. Brown and amber increase contrast and feel warm, great for driving and overcast days. Green sits in between. Pink, yellow and blue tints are usually light (category 1–2) and chosen for the look rather than for protection: perfect for evenings and city streets, not for a day in the sun.
Women's Cat-Eye Green/Brown Sunglasses - Gentle Monster Crepe 01
Green and brown on a cat-eye: a lens chosen for warmth and contrast.
Unisex Oval Brown/Blue Sunglasses - Gentle Monster Cuscus BRC20
Brown and blue on an oval frame: colour as part of the design.
Photochromic: one pair for everything
Photochromic (or "transition") lenses darken in sunlight and clear up indoors. Convenient, but they react slowly in cold weather and barely darken inside a car, because the windscreen blocks the UV that triggers them. Rare on designer sunglasses; if you need them, ask an optician to fit them into a frame you love.
Quick guide: which lens for which day
- Everyday, city: category 3, grey or brown, polarized optional.
- Driving: category 2 or 3, polarized, brown or grey. Never category 4.
- Beach, boat, snow: category 3 or 4, polarized, mirrored if you like.
- Evenings, indoors, photos: category 1–2, gradient or light tint.
Taking care of your lenses
Rinse with lukewarm water, dry with the microfibre cloth that came in the box, and never with a T-shirt or a paper towel: both scratch. Store the pair in its case, lenses up, and keep it out of the car in summer, heat warps acetate frames and damages coatings.
Questions about a specific model's lens? Write to contact@skyeshades.com. Every pair ships free with tracking and can be returned within 14 days.