I use Fondx Black fondant and I can't see any fading on my black display cake. It has been sitting out in my dining room for about a year. This room gets morning sun. If, in the future I ever see any fading, I will do exactly what @elizabethscakecreations suggested.
Thank you Elizabeth and Nancy for your comments. I have virgin Ice black fondant that I want to use. I think I will try it out. If it doesn't last long, it will be a lesson learned for what I can do. Better try it, then never know :) Thanks for all your help.
Quote by @%username% on %date%
%body%