Blu Ray discs with bronze/gold color bottom?

[PantsHalo]

I've been going through and selling off a lot of my old DVDs and some blu rays. I've learned to spot disc rot via staining and bronzing and the like.


However, I've found that a whole lot of blu rays I have, ranging from between 2-10 years old, are somewhat bronze or gold colored on the bottom. They don't have any signs of wear or deterioration or staining, the color is all pretty much solid and flat.


Is this disc rot? Or is this color natural for certain blu ray discs? There's no real consistency in terms of which discs are bronze colored, ranging from Sony to Universal to Warner Brothers to Arrow. Should I be worried nonetheless?


EDIT: I might be dumb as hell as I realize a lot of this might not actually be the bronze color but just the purple-ishness of blu rays reflecting off the lighting to make the disc color seem slightly bronze in tone (the light in my room is very warm)