1.Note that the color of the lenses doesn't just affect your fashion statement, it affects how well you detect contrast and differentiate colors. Some colors enhance contrast, which can be useful; however, this is often at the expense of color distinction, which can cause problems (when you're driving, for example, and need to be able to clearly differentiate the colors of a traffic light). Some sunglasses even come with interchangeable lenses so you can change the color easily, depending on what you're doing.

· Gray lenses reduce light intensity without affecting contrast or distorting colors.

· Brown lenses partially enhance contrast by blocking some blue light. Good for snow sports. Also generally good for hunting in bright light, against open backgrounds.

· Amber/yellow lenses significantly enhance contrast because they block most or all blue light, and that makes them popular among hunters who benefit from that contrast when looking at targets against the sky. They're bad, however, for any activity that requires color recognition (like driving!). Good for snow sports.

· Red/orange lenses are good for snow sports but only on overcast days. If you're a hunter, orange lenses are good for clay targets against open backgrounds.

· Violet lenses are good for hunters who need to see clay targets on a green background.

· Copper sunglasses will mute the sky and grass against a golf ball.

· Blue and green sunglasses enhance contrast with a yellow tennis ball.

2.Check for distortion. Hold the lenses up to a fluorescent lamp. As you move the sunglasses up and down, check that wave distortion doesn't happen. If it doesn't happen, this is a good sign.