The Nazar

Called nazar boncuğu in Turkey, the Nazar, also known as the Evil Eye stone, is a talisman meant to ward off evil and provide protection to the wearer in all aspects of their life. What is most interesting is that it isn't a folksy thing or a rare sighting to see someone wearing it, but rather it is a prevalent part of Turkish culture. From the reading I've done about it, it seems that everywhere you go you'll find people wearing the strange symbol; earrings, bracelets, necklaces, anklets, charms in all sizes adorn people, their homes, cars, and even children in order to protect them from the Evil Eye. It's even painted on the side of some Turkish airplanes, to protect the plane and passengers.
People have believed in the Evil Eye since before the ancient Greeks rose to prominence, finding a niche in almost every society, but belief in the evil eye is strongest in the Middle East. This is probably due to a statement by the prophet Mohamed saying "the influence of an evil eye is a fact..." One way or another, the Evil Eye found a root in the middle east, and has stayed there ever since.
People believe that the Evil Eye is a curse, given intentionally or unintentionally by someone else. The one who bestows the curse is said to look upon the soon to be afflicted person with an evil look, and misfortune will come to those caught in the gaze. The effects vary, but people seem to agree that it causes illness, wasting, dehydration, and death. In order to protect against this, the Turks created the Nazar.
They are often given as gifts to friends who have just had a baby, or moved into a new home, though sometimes they are given to foreigners as protection during their stay. The people of Turkey are very cautious about the Evil Eye, and so sometimes one Nazar isn't enough.