In the room there are stained glass windows in which gold is the predominant colour. What colour will suit best to minimize this? What affect will this have on the colour that I choose?
Stay away from dark colors as that will only emphasize the gold color. If it's a light gold try painting the walls a shade of yellow or even orange – if you're the adventurous type. Painting the walls a shade that has a golden base will de-emphasize the gold and help it blend in.
What you need to find is a good color to complement the gold, this way the gold doesn't stand out or look odd. In the color wheel this would be a purple or dark blue. Another option is a darker red, even though by definition red isn't a complementary color to gold I feel that a darker orange-ish red goes well with yellow/gold. Kind of like a ketchup mustard combination. These options will make the overall tone of the room fairly loud, but I feel like this is the best option since gold is so loud itself.