In the Iconographic tradition a gold background represents the heavenly realm but that is not always the case in the Gothic form. Backgrounds of different colors are used to show a change of scene or to differentiate states of being.
Hold the Line! The Iconography and Workshops of George Kordis
George Kordis is offering classes in Athens and Crete this summer in English, see writingthelight.com. For those who don't have the resources and time to get to Greece, Kordis is now offering online courses at iconographytoday.com/en.