Gemstones have had an important place in many religions for centuries. In the Judeo-Christian tradition, the Bible refers to twelve stones set in the breastplate of the high priest, symbolizing the twelve tribes of Israel. In Hinduism, nine gemstones are identified as corresponding to the
nine planetary Gods in Vedic astrology.
In Islam, a practice of wearing gemstones developed from legends associated with Ali, the cousin and son-in-law of the prophet Muhammad, and the first (or perhaps the second) convert to Islam. There is a tradition that Ali wore four rings on his hand with four different gemstones, expressed by the Arabic names Aqiq, Yaqut, Feruz and Hadid Theen.
Aqiq (sometimes spelled Aqeeq) is believed to refer to the gemstone Carnelian. This is generally regarded as the most important gemstone in Islam. The Prophet was said to have worn a silver ring on his right hand with an Abyssinian stone (probably a type of agate, such as carnelian), with the stone facing toward the palm. Ali was said to wear a carnelian to protect himself from enemies and misfortune.
The term Yaqut is less clear. It is often translated as Opal, and it is said that Ali wore Yaqut for "beauty and dignity." But many scholars believe the term Yaqut refers to Ruby, and this view seem more widely accepted.
Feruz (or Feroza), on the other hand, unambiguously refers to the gemstone Turquoise. It is said that Ali wore turquoise "for obtaining divine help and victory." There is an Islamic tradition that if a person prays to Allah while wearing rings set with Feruz and Aqiq, Allah does not turn the prayers down unanswered.
Hadid Theen is believed to refer to the gemstone Hematite. It is said that Ali wore this gem for strength. The Islamic lore cautions against wearing hematite constantly; instead it should be worn for protection when confronting a tyrant or oppressor.
Finally, the fifth stone of significance in know as Dur-e-Najaf. This is generally thought to be a type of quartz or rock crystal from the Najaf al-Ashraf area of Iraq. The legend is that Allah had made this stone easily available so that both the rich and the poor could wear and benefit from it.