When I started collecting as a child, I bought this PINK / PURPLE mini holly at an insulator show with my dad. It sat on a window seal for almost 15 years. Recently it's home changed to on top of my desk and to my horror I discovered it had turned LIGHT GREEN AQUA! For a split second, I actually thought it changed color...

Thanks to the new "green" world we live in almost every light in my apartment is now fluorescent. My guess is that metals in the glass mixture react differently to sun / incandescent verses fluorescent light. (I first heard about this type of glass reading the suspect EC&M articles...)

The left picture is in incandescent the right one is in fluorescent light.