Use of the symbol dates back to ancient civilisations – the earliest evil eye amulet is recorded from 3,300 BC – and the idea is that those carrying or wearing an evil eye charm are protected from any malevolent glare (or evil eye) that might cause misfortune, bad luck or injury.

From Egyptians and Etruscans who used to paint the eye on the prows of their ships to ensure safe passage, to Turkey, where it's still traditional to bring an evil eye token to newborn babies (as young children are believed to be the most susceptible to the evil eye curse), ocular talismans have been adopted as a form of eye-for-an-eye protection against harm by Jewish, Christian, Muslim, Buddhist and Hindu societies for thousands of years.

Source: www.standard.co.uk