Have you heard of sunglasses with flash lenses?

Flash lenses are a type of mirrored lens, with one subtle difference to other mirrored lenses: the treatment coating is less dense, meaning the mirrored effect is thinner, less strong, and more elegant. The flash effect adds a touch of colour to the lens, which becomes visible when from different angles, for example when moving your head. Also, these lenses reflect any excess light that passes through them, making them very useful for snowy areas or sunny areas near the sea.