For our beloved 1977 Star Wars, this does mean we can’t be 100% certain of the quality of the extant prints. Lucas obviously had the best one.
No, Lucas had to borrow a 35mm IB Technicolor print from a collector to use as a reference for the 97SE. This particular collector was fortunate enough to receive his print back from LFL when they were done.
the Technicolor prints are a bit off in a variety of ways. I’m thinking, since they were shutting down production in 77, that they are probably print control issues rather than fade issues.
The Technicolor IB process introduces color changes independent of quality control. IB Technicolor prints tend to have greater contrast, saturation, and are shifted toward green. They may be fade-free, but this doesn’t mean that they’re truly accurate to their source.