There are two reasons to select a color for your sunglasses. One is for fashion and the other is for function.
If you are strictly going to wear them for a specific activity, like cycling or fishing, then the color should be dictated by your environment. Below is a reference to simplify the choice of sunglass colors.
Brown, gray, green—Brown lenses are referred to as color-neutral. Essentially this means they cut down overall brightness without distorting colors, giving a dimming effect to the bright sun. Use these darker shades to cut through the glare and reduce eyestrain while in bright to moderately bright conditions.
Yellow, gold/amber, Yellow. These lenses will provide less overall brightness protection, but improve quality of vision in moderate-to-low level light conditions. They provide excellent terrain recognition and depth perception. They are the perfect chioce for skiing, snowboarding and other snow sports. They also enhance contrasts in flat-light conditions, making them effective for everyday wear.
Rose/vermilion, Rose, and vermilion-colored sunglasses will make the world around you seem brighter. They provide excellent low-light visibility and enhance contrast making them the perfect chioce for skiing and snowboarding in cloudy conditions. They also enhance the visibility of objects against blue and green backgrounds. This shade of lens is the perfect choice for driving or exploring in low light areas such as dense forests.