What color is the Custom?
I don't know what Gibson calls that color today. But that LP looks a lot like what vintage Pelham Blue looked like, after it faded and turned greenish. It seems like they tried to mimic that.
He is correct. It is called "Antiqued Pelham Blue" and is meant to capture what happens to pelham blue after 50 years. They actually painted it pelham blue and then added yellowing coats till it landed at the grennish tint you see in the pic. One of the nicest if not THE nicest opaques I have ever owned.