This is a supporting image for the Annunciation Diptych painted by Jan van Eyck in 1433-1435. This image is part of the Ghent Altarpiece, also known as the Adoration of the Mystic Lamb or the Lamb of God. This altarpiece consists of 12 panels painted on both sides. Dependant on which panels were opened or closed, it would portray a different story. This piece was painted by the two brothers Hubert and, the painter of the Annunciation Diptych, Jan van Eyck in 1432. This panel is depicting the archangel Gabriel on the bottom and the Prophet Zacharias above. The Virgin Mary is two panels away from the archangel Gabriel and when the Ghent Altarpiece is closed, it forms the Annunciation. Unlike the Annunciation Diptych, this piece of the Ghent Altarpiece is in colour and the angel Gabriel doesn’t look as if he is made of stone. This piece is kept at the Saint Bavo Cathedral in Ghent, Belgium.
Image Credit: http://hoocher.com/Jan_van_Eyck/Jan_van_Eyck.htm