Blue lens fog lights?

[ourkid]

Just been looking through the photo gallery (first time),and on the first page is a Mistral,same colour as mine,but has blue front fogs.Silly question - are these road legal,are they tinted/painted or bought new this colour?

Mine are yellow - not sure if they are factory or aftermarket - anyway,i hate them.

 

[Ian Hunt]

I always wondered what the advantage of blue lenses is, they seem very common.