gems, turquoise, Persia, Iran, Persian turquoise, glyptic, Roman gems, ancient gems, callaina

In the final volume of his encyclopedic Natural History, Pliny the Elder devoted extensive attention to gemstones, including a detailed account of the “pale green callaina.” He describes its occurrence beyond India among the Caucasus tribes, where it is found in large, but porous and flawed, formations. A purer variety comes from Carmania, yet in both regions, the stone appears as eye-shaped swellings loosely attached to icy cliffs. The local tribes, too indolent to climb, dislodge the stones by shooting at them with slings, a practice that not only supplies their taxes but also forms the basis of their wealth and social pride. Some become adept, striking fine stones on their first try; others reach old age without success. The callaina is then drilled and shaped, being relatively easy to work, though finer specimens lose their color upon contact with oil, unguents, or even wine, while lesser ones retain it. Pliny notes its susceptibility to imitation in glass—no gem is more easily counterfeited. Today, this mineral is identified as a cupreous basic aluminum phosphate (hardness 5–6 on the Mohs scale) associated with copper deposits and once found in regions like the Sinai and Iran, both ancient centers of copper mining and home to nomadic peoples who favored it in their jewelry. Though Pliny’s name for it, “callaina”—meaning blue-green—has been forgotten, the stone endures under the name turquoise, a reference to the Turks who once controlled its trade. Many of the qualities Pliny observed remain key to turquoise’s value: its frequent veining, rarity in pure large pieces, softness, and color instability. While the blue shades prized today were less valued in antiquity, Pliny’s warning about glass imitations remains remarkably relevant.