Book VI gems: diamond, emeralds, sapphire, topaz, chrysoberyl, carbuncle, jaspis Page 139



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	the fulgor of the gem is the color of gold. Chrysoberyllus is also named choaspitis from a river.¹⁷ This gem is also said to have a golden-green fulgor. Chrysoprasius is the third species and its name comes from gold and the juice of the leek. It is lighter colored than chrysoberyllus. The fourth species is hyacinthizontes, so named because it is similar in color to the hyacinthus; the fifth, aerodes, because it is similar in color to the sky;¹⁸the sixth, cerinus, because it is similar in color to wax; the seventh, olea-genus, because the color is similar to that of oil; and the eighth, crystal-linus, because it is colorless. Beryllus may contain the same flaws as smaragdus as well as the characteristic flaws called "membranes." Because of its color beryl tends to be dull unless the dead and lifeless appearance is enlivened by reflection from the angles. For this reason gem cutters give a hexagonal form to all of these stones and make cylinders from them more often than other gems. The cymbia (goblets) of India are made from chrysoprasius. The finest gems have the golden center in the top of the stone. The others are usually drilled to remove any white core and if they are only moderately transparent they are strung on elephant's hair. If they are even less transparent gold is added to increase the transparency.¹⁹ Diadochos is similar to, if not actually the same as, beryllus since the writers who describe this stone do not say in what way it differs from the latter.²⁰ Prasius (prase) which is called prasitis by Theophrastus is a lighter green than the beryl which has the pure green color of the sea. It has the color of the juice of the leek and the name comes from this (τράσον, a leek). Eumetre, which the Assyrians call the gem of Belus after their most sacred God, is leek-green and is seen to be the same mineral as prase. This stone is translucent but not very brilliant. For this reason it is classed among the valueless gems. There are three species. The first is moderately green, the second characterized by blood-red spots (bloodstone) and the third by three white twigs. Prase has the same flaws as beryl. It is found in the silver and copper mines of Germany. Heliotropios (heliotrope) is another species of prase which is also leek-green.²¹ It differs from one species of prase in that it has blood-red veins through it instead of spots. It is found in Cyprus, Africa and Ethiopia. " The Choaspes river in Persia. ¹⁸ Pliny and other writers give this name as aeroides. This would be called aquamarine today. ¹⁸ This is a good description of beryl and of the numerous varieties including the bluish-green aquamarine, the golden-yellow heliodor, etc. Crystals are found of extraordinary size. Flaws are common and the color is often irregular. ^!0 For more than 2000 years diadochos was a mineral noted for its magical properties. It is interesting to note that the name (diadochite) is given today to an entirely different mineral, one with properties that are unusual if not unique. ⁸¹ Prase and plasma are more or less identical varieties of cryptocrystalline quartz, plasma being slightly less translucent than prase and somewhat brighter green. Heliotrope is identical with bloodstone, essentially prase or plasma containing spots of red jasper.