This is an amulet designed specifically to repel the evil eye. Originating in Turkey, the Nazar is found in shops frequented by tourists. It is a pretty piece of circular blue glass, with additional dollops of glass set in a concentric circle of blue and white to represent the eye. Traditionally, the Nazar is hung in windows or doors ways to repel undesirable influences.
Nozedar Adele, The element encyclopaedia of secret signs and symbols, 2008, Nazar, p 148