With gold that has a mirror finish I find it is better to scan using a light background colour. If it is circulated then you are better off with a blue background.
I had years of color study working in coloring plastics for Mercedes cars to match their leather color etc and I studied Johannes Itten on colors and could read
spectophotometer graphs ( what they now call histograms in photoshop )
The eye is easily deceived . Put a slightly neutralised blue color on a real blue color background and your eyes will tell you it is dirty purplish like .
So I am completely flabbergasted
My canoscan8800F comes with three drivers a standard , a canondriver , and Silverfast a professional photographers driver
The Canondriver will render the image independant of the background ( scan will look the same with or without background) whilst Silverfast will show you what the deceived eye sees ; that is the image as seen by the eye on that background but totally different from the image without background
On the left is what the eye would see if poster and background where separated and on the right is what the eye really sees when you put one on top of the other ( now this is the same scanner with standard settings and two different drivers )
( What you really see will depent on your gamma setting etc of your LCD screen unless you have an old Video screen )