The artwork you are referring to is the “Deesis Mosaic,” featuring John the Baptist, created by Byzantine artists around 1261. It is a mosaic medium that belongs to the Late Byzantine/Palaeologan Renaissance period within the Byzantine art movement. This piece is part of a religious painting genre and is located in the Hagia Sophia in Istanbul, Turkey. The Deesis Mosaic is a series of mosaics within the Hagia Sophia that capture significant religious figures and themes.
The mosaic depicts John the Baptist, a prominent figure in Christianity known for baptizing Jesus. John is presented in a traditional Byzantine style, with a halo around his head signifying his saintliness and a solemn, dignified expression. His fingers are raised in a gesture that denotes teaching or blessing. The rich gold in the background indicates the heavenly realm and was a common feature in Byzantine religious art to convey the divine nature of the depicted figures. The artistry seen here highlights the sophistication and spiritual depth of Byzantine mosaic work from this period.