This diptych is an outstanding example of grisaille painting. Here, van Eyck deliberately rejects the use of primary colours, painting the figures in white on a black background to create the illusion of a sculptural group. The painting forms part of a series of small-format works probably intended for private devotion. The inscriptions on the frames—a common device in van Eyck's panels—refer to the subject of the diptych: the first and last sentences of the dialogue between the Archangel ('Hail, full of grace, the Lord is with thee' [I-28]) and Mary ('Behold the handmaiden of the Lord; be it unto me according to thy word' [I-38]), taken from the Gospel of St Luke. The frames were painted by the artist using trompe l'oeil effects and playing with the exquisite set of mouldings that decorate the panel.