…like sapphires in colour, only that it is paler and more closely resembles the tint of the water near the sea-shore in appearance.
(Pliny the Elder: Natural History, XXXVII.56)
It is found in the countries that lie at the back of India, among the Phycari, namely, who inhabit Mount Caucasus, the Sacæ, and the Dahæ. It is remarkable for its size, but is covered with holes and full of extraneous matter; that, however, which is found in Carmania is of a finer quality, and far superior. In both cases, however, it is only amid frozen and inaccessible rocks that it is found, protruding from the surface, like an eye in appearance, and slightly adhering to the rock; not as though it formed an integral part of it, but with all the appearance of having been attached to it. People so habituated as they are to riding on horseback, cannot find the energy and dexterity requisite for climbing the rocks to obtain the stones, while, at the same time, they are quite terrified at the danger of doing so. Hence it is, that they attack the stones with slings from a distance, and so bring them down, moss and all. It is with this stone that the people pay their tribute, and this the rich look upon as their most graceful ornament for the neck. This constitutes the whole of their wealth, with some, and it is their chief glory to recount how many of these stones they have brought down from the mountain heights since the days of their childhood. Their success, however, is extremely variable; for while some, at the very first throw, have brought down remarkably fine specimens, many have arrived at old age without obtaining any.
Such is the method of procuring these stones; their form being given them by cutting, a thing that is easily effected. The best of them have just the colour of smaragdus, a thing that proves that the most pleasing property in them is one that belongs of right to another stone. Their beauty is heightened by setting them in gold, and there is no stone to which the contrast of the gold is more becoming. The finest of them lose their colour by coming in contact with oil, unguents, or undiluted wine even; whereas those of a poorer quality preserve their colour better. There is no stone, too, that is more easily counterfeited in glass. Some writers say, that this stone is to be found in Arabia also, in the nest of the bird known as the “melancoryphus.”
(Pliny the Elder: Natural History XXXVII.33)
In response to Ailsa's travel theme: Turquoise.