There are at least three different capes that were made for ROTJ. Each is slightly different from the next. There is the AOSW cape that appears to be the one worn on the skiff battle scene
The MotM which I have not seen yet in the movie
There is also the cape in Jabba's Palace that is the one on the New SideshowCollection Doll.
they are 30x36 and the orange is no more then a hands wide. Thats what i tend to go by hehe. but if some one knows the proper dimensions please post it.