Hi all,
I've just checked the ROTJ duel on Youtube and the blade varies in colour throughout but as I have mentioned in other threads the technology to create the blades isn't perfect and other light in the shot can affect the applied colours of the saber.
If anyone has heard of Adobe After Effects this is the type of software used to put graphics on top of news channels, and LucasFilm use a similar process to "Paint" the blades onto the shot. The image beneath the blades sometimes show through slightly especially if bright enough. Motion blurring also complicates the issue. Try to look at the blade when it is motionless.
For Tyeth