I have several around the house.

The Turkish Evil Eye Pendant is actually a stone bead, which is worn to protect oneself
from evil looks. The stone is an amalgamation of molten glass, iron, copper, water and salt.
This particular combination of minerals and metals is believed to provide a shield from the
forces of evil.

The Evil Eye pendant has the symbol of an eye worked upon it. The symbol of the eye is
regarded as a potent amulet for protection against evil forces in almost every culture of the
world like Jewish, Islamic, Hindu, Buddhist and Christian. Thus, in Turkey, you have an
eye for an eye.

http://www.nazarcapitola.com/evileyestory.html

It is believed that the Evil Eye Bead deflects the negative energy that is being directed
towards a person onto itself, thus dispersing its powers.

The Evil Eye Bead is blue in color and the age-old Anatolian belief is that it is actually the
blue color of the stone, which holds the real shielding power and absorbs the negative
energy.

This is not surprising since the people in many Mediterranean nations ardently believe in the
protective powers of the blue color. That is why; front doors of houses in these
Mediterranean countries are painted blue to ward off evil spirits.