How to Tell if Sunglasses Are Really Polarised (the Fish Card Test)

"Polarised" is printed on lots of sunglasses, but how do you know it's real? Here are three quick tests you can do at home in under a minute.

Why polarisation matters

Polarised lenses cut glare: the harsh, reflected light that bounces off water, sand, roads and car windows. Less glare means less squinting and more comfortable eyes, especially at the beach. (Polarisation is different from UV protection. For that, check for UV400. Here's the difference.)

Test 1: The phone screen

Look at your phone or a laptop screen through the sunglasses, then slowly rotate the sunglasses (or the phone) about 90 degrees. If the lenses are polarised, the screen will go noticeably darker, sometimes almost black, at one angle.

Test 2: Two pairs crossed

Hold two pairs of polarised sunglasses in front of each other and turn one pair sideways. Where the lenses overlap, they'll go dark. If nothing changes, at least one pair isn't polarised.

Test 3: The secret fish card

Every pair of Baby Sunnies comes with a secret fish card. Look at it with your bare eyes and it seems blank. Look at it through your Baby Sunnies and a hidden fish appears. Take them off and it vanishes again. It's polarisation you can actually see, and kids love it.

One more thing to check

Polarised doesn't automatically mean UV protection. For children's sunglasses, always look for UV400 lenses, which are designed to block 100% of UVA and UVB rays. All Baby Sunnies are both polarised and UV400.

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