Photchromatic sunglasses are the current rage of the season. A photocromic or a photchromatic lens changes its color according to the varying light conditions. For instance, when there are bright light conditions, the lens becomes darker in color and when there is comparatively less light, the lens becomes lighter in tint. This is made possible with the use of an active ingredient called Silver Halide that is mixed with the materials of the lens. Silver Halide is what gives the lens the capacity to change colors, depending on the intensity of the surrounding UV rays. Sunglasses of various brands, including the Gianni Versace sunglasses can be bought from online resources. However, be sure to buy Gianni Versace sunglasses only from authorized dealers.