Dying A Formal Dress White??

Hi :)
I`m newly engaged and my freind and I found the perfect dress for me at goodwill. It could not fit any better, it`s exsactly the style I wanted, and it`s absolutely georgeous. It`s not outdated at all or anything....it must have been a prom dress or something becaue it`s very simple but it`s exactly what I want. Th only problem is, it`s like...a light mint green color. It`s pretty....btu not for my wedding gown. It`s made out of an acetate and I was wondering if anyone`s ever heard of dying a formal gown white?? My freinds mom thinks that you would have to take the color out and then dye it white...because she says white is a color. I certainly wouldn`t try it myself, but has anyone ever had any luck with a similar situation??? Thanks all, God bless and take care!!!