The following description was prepared by William Gross:
From earliest times, man has tried to protect himself from misfortune by the use of objects which he considered holy or otherwise (e.g., magically) potent. Amulets and talismans are items generally worn around the neck or wrist, carried in a pocket or purse or hung on a wall. They are meant to protect or aid those who carried or wore them. The Hebrew word for amulet, kame‘a, has the root meaning "to bind". Jewish amulets are usually comprised of texts (either letters or graphic symbols) that are inscribed on some sort of material; some may also contain plant matter or precious stones. The texts of amulets usually include holy names that are believed to have the ability to affect reality, along with incantations summoning angels or other magical powers. For the most part, an amulet has a specific purpose: to ease childbirth, facilitate recovery from illness, improve one’s livelihood, and so on, but in the modern world many are also made for general protection.
This is the typical form of a "hamsa", in cast silver, as used in Tunisia, with one of the names of God inscribed on it. The star and crescent in the middle strongly indicate the origin in a Muslim country. The use of the "hamsa" (the hand of Fatimah) was a common amuletic device in North Africa in general and, most prominently, in Morocco, Algeria and Tunisia. While in Tunisia, the amulet was most often crafted in cast metal, in Morocco it was usually made from sheet silver. As contrasted with the Middle East and Asia, where the metal amulets contained inscriptions, sometimes quite long and for specific reasons, the amulets of North Africa were of a more general protective nature and mostly without inscriptions. The crescent and the five-pointed star are both devices which lend protective power to the hamsa.
The hamsa is arguably the most popular form of amulet against the Evil Eye and is used in a large number of countries in the world of Islam. Probably originating in Moslem Spain of the 12th or 13th century, it crossed the sea to Morocco with the expulsion of 1492 and spread across North Africa to the Middle and Far East.