[header] How to tell if sunglasses are polarized [title] Find a reflective surface that produces glare when light is shining on it. [step] You could use a reflective tabletop, a mirror, or other shiny, flat surface. Make sure the glare is noticeable even from about 2 to 3 feet (60 to 90 cm) away. 
[substeps] If you need to produce glare, you can turn on overhead lights or shine a flashlight on a reflective surface. [title] Hold your sunglasses about 6 to 8 inches (15 to 20 cm) in front of your eyes.