Most sunglasses come in 4 colors:
Grey – Considered the best for overall light reduction. All colors in the visible light spectrum are reduced equally leaving colors to visually remain the same. Grey is a great choice for light sensitive individuals and for use under bright sunny skies.
Brown – Brown cuts the blue frequencies of the visible light spectrum while enhancing the red frequencies. The result is a lens that tends to bring out more definition in distance vision. Brown is a great choice for a combination of clouds and sunny skies.
Rose – Rose has similar properties to brown. But, the effects are more intense. Rose is best when cloudy skies are prevalent.
Green – Arguably, the most traditional lens coloring for sunglasses. However, green has the least specific color purpose and is considered a great general purpose color. For decades, green was the best and most practical way to color glass lenses. Today, it is a great way to maintain that classic retro sunglass look.