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BOOK VI
125
placed in water and viewed from a distance, it appears to be larger than it actually is. Gold and silver coins placed in water show this same phenom­enon for the brilliancy of the metal tints the surrounding water just as the smaragdus tints the surrounding air. Stones of poorer quality are not so green in the sun although they are transparent. Such stones came from Attica according to Pliny. Some stones, when inclined, are more or less green and bright such as those mentioned by Pliny from the copper mines of Carthaginia as well as the smaragdus surrounded by white veins of the mineral they call galactites.
Smaragdus contains a great many flaws. First, the color is not uniform being bright green in one part and either dark or light green in another or the green color does not extend through the entire crystal. The interior or the edges may be white. These gems are called clouded. The transparency may vary and one part may be completely transparent another part not. Pliny says that the Persian crystals are not absolutely transparent, as­suming that the crystals he mentions are smaragdi, as he himself believed. These may have belonged to a translucent species of smaragdus which includes the Median stones. As described by Pliny these latter stones contain images of various objects such as the poppy, birds, feathers, small animals as well as the images shown by other translucent gems and marbles, for example, agates and green marble. As regards the body of the stone, it is not always perfect and may contain flaws such as hair, "salt," lead rust, pulp and flaws peculiar to this gem. Some of the Cyprian gems are various shades of bluish gray. The stones from Attica gradually lose their green color and appear to die of old age. These stones are also injured by the sun. On the other hand the stones from Media that are not uniformly green can have their color improved by placing them in wine or oil.
Although smaragdus is rarely hard Pliny writes that the stones from Scythia and Egypt are so hard they cannot be injured. The Cyprian stones are not so hard. The Carchedonian stones, as well as all the rest, are so fragile that gem artisans are more reluctant to set these stones in rings than any other. The gems are cut cabochon, flat or concave. One very famous gem is in Genoa with the shape of a small shallow dish. A similar smaragdus is in the monastery of Narbo, Gaul, on the plain of Lyons. These are certainly very large gems. The gem in the small shrine to Wenceslaus at Prague, Bohemia, is not small since it is over nine inches long. There is a longer gem at Magdeburg which forms the base for the small tower-shaped golden chest in which the sacrament is carried. They say that the handle of the dagger of Otto I was a smaragdus. Although some smaragdi have been perforated as a rule they are not so large. The largest are the Cyprian stones which very rarely are found large enough to carve into small figures. According to Theophrastus they are usually small. A most extraordinary gem was found in Cyprus which was half smaragdus and half jaspis. This, as well as all other gems that have formed from different essences, contains an unusual number of flaws.