วัสดุเทอร์ควอยซ์Turquoiseفیروزه

The claim made for turquoise almost everywhere it is worn is the same one, and it is unusual: the stone reports. Writers on the ancient cultures that used it — Egypt, the Aztecs, Persia, Mesopotamia, the Indus Valley, Shang China — record a common belief that turquoise held prophylactic qualities, that it changed colour with the wearer's health, and that it protected the wearer from untoward forces. A porous stone that darkens with skin oil and sunlight will in fact change, which is a rare case of a claim and a material property lining up.

In Iran it was the national stone for millennia, worked into everything from turbans to bridles, and used on domes because its blue stood for heaven on earth. Persian turquoise was often engraved with devotional words in Arabic script and the letters inlaid with gold. The Persian style went to India with the Mughals.

In Mesoamerica the Aztecs took turquoise as an embodiment of fire and gave it properties of heat and smokiness, inlaying it with gold, quartz, malachite, jet, jade, coral and shell into mosaic masks, some built on a human skull, and into knives and shields, bedded in resin, bitumen and wax. In the North American Southwest the Pueblo, Navajo and Apache prized it for amuletic use; Apache tradition holds that the stone gives an archer dead aim, and in Navajo use it is described as "a spiritual protection and blessing". Writers on the stone credit the Ancestral Puebloans of Chaco Canyon and the surrounding region with prospering greatly on producing and trading it.

Egypt mined it in Sinai and then imitated it: the blue-green glaze on faience exists in order to look like this stone and like lapis lazuli.

Tibetan and Mongolian silver and gold work still sets imported turquoise beside coral, with a greener hue preferred. Writers on the stone report both halves of the present trade without settling it: most pieces made today are roughly polished cabochons set simply in silver, meant for inexpensive export to Western markets, and are probably not accurate representations of the original style. The stone has also been devalued in finer grades by treatments, imitations and synthetics. Mining boomed and broke: prices peaked in 1890 and had collapsed by 1912, ending large-scale operations.