Strangest thing! I've got a Nightforce compact NXS 2.5-10X32. Pretty much brand new; mounted once, sent back to nightforce for an issue with the eyepiece coming loose, got it back and wrapped it in a green cotton T shirt for protection, and put it in the closet till I could get around to mounting it on a permanent home...........just looked at it today and the damn thing has turned purple......everywhere except where the lens covers were at.....it's still black underneath where they were!! Gun cleaning solvent didn't budge it at all, possibly some sort of chemical etching........maybe a reaction to the green cotton shirt.?? Looks like it may be headed back to Nightforce for a second trip. You can see on the objective bell how the color goes from purple to black where the lens cap was, then to a darker black where the metal changes.................Weird, just damn weird! I must have some of the worst luck sometimes.