Choosing the colors of sunglasses that look best on you is much like choosing the colors of your clothing. We all have either a warm or cool undertone to our skin – identifying this undertone can help you discover what shades of color best complement your natural tone.
How do you determine if you your skin is warm or cool?

The easiest way to figure out if you should lean towards warm or cool colors is to look at the underside of your arm in natural daylight. If you have a pink or rosy undertone to your skin and bluish veins, you have cool-toned skin. If you have a golden or apricot undertone and greenish veins, you have warm-toned skin.
This color wheel from colorindesign.net shows which colors are considered cool and which are considered warm. When it comes to sunglasses, keeping your skin tone in mind is most important, but you might also want to consider how colors might complement your hair color.
TIP: In terms of sunglasses (and clothing), cool-toned wearers should gravitate towards frames in blue-based hues, while warm-toned wearers should look for yellow-based hues.
Sunglasses Color Suggestions for Cool and Warm Skin Tones
For those of you who have cool skin tones…
Blue, pink, plum, magenta, tortoise, green, silver and black frames or lenses look best.
Example: Angelina Jolie, Sarah Jessica Parker, Cameron Diaz

For those of you who have warm skin tones…
Gold, copper, orange, brown, tan, olive, dark red and off white frames or lenses will be most flattering.
Example: Lindsay Lohan, Beyonce Knowles, Nicole Richie

Skin Tone References:
http://www.womenshealthcaretopics.com