In folk magic the
horned hand (in Italian - mano cornuto) is a sign against the evil eye. Our
sterling silver amulet is a traditional design of a hand with the index finger
and little finger extended, while the two middle fingers are held folded down
by the thumb. The horns point downward in order to send or ground the
evil eye. In folk magic it was common to use this gesture to block envy,
which was believed to cause illness.
You can read more in "the Cimaruta and Other Magical Charms From Old Italy" by Raven Grimassi.
A self-published book .