Lapis Lazuli A Tumbled Gemstone

Soft (Mohs 5 to 5.5) and slightly porous, and its calcite is attacked by acids. Avoid soaking, salt water, acids, ultrasonic cleaners and household cleaners; a quick rinse, dried right away, is fine. Not known to be hazardous to handle.

Lapis has been dug from the Sar-e-Sang mines in the Kokcha River valley of Badakhshan, Afghanistan, for more than 6,000 years, making them some of the oldest continuously worked mines on Earth. Carried west along caravan routes, it reached the royal tombs of Ur and the workshops of Egypt, and much later crossed to Europe, where it was ground into ultramarine. Deposits in Chile, Russia's Lake Baikal region and Tajikistan followed, but Afghan lapis still sets the standard for color.

Lapis lazuli is a rock, not a single mineral. Its blue comes from lazurite, a sulfur-bearing member of the sodalite group, mixed with white calcite, brassy flecks of pyrite and smaller amounts of diopside, sodalite and other minerals. It forms by contact metamorphism, where limestone or marble is altered by heat and mineral-rich fluids. The finest grades are an even, saturated blue with little calcite and a fine scatter of pyrite.

• In the Sumerian poem of Inanna's descent to the underworld, the goddess sets out wearing lapis beads at her throat and holding a lapis measuring rod, symbols of divine authority she must surrender gate by gate.
• Egyptian craftsmen inlaid lapis into royal treasures, including the eyebrows and eye lines of Tutankhamun's gold burial mask, and its gold-flecked blue was long linked with the night sky and the heavens.
• Renaissance painters ground the finest Afghan lapis into ultramarine, a pigment that could cost more than gold, and patrons often reserved it for the blue robes of the Virgin Mary.