The “Serpent Isle,” in the Red Sea, was stated by Agatharcides to be the source whence came the topaz (chrysolite); here, by the mandate of the Egyptian kings, the inhabitants collected specimens of this stone and delivered them to the gem-cutters for polishing.[65] These simple details are elaborated by Diodorus Siculus into the legend that the island was guarded by jealous watchers who had orders to put to death any unauthorized persons who approached it. Even those who had the right to seek the gem could not see the chrysolite in daytime; only after nightfall was it revealed by its radiance; the seekers then marked well the spot and were able to find the stone on the following day.[66] From this Egyptian source, and possibly from others exploited by the Egyptians, have come the finest chrysolites (peridots, or olivines), the most magnificent examples of this gem. These found their way into the cathedral treasures of Europe, evidently by loot or trade at the period of the Crusades, and are generally called emeralds. Those most notable are in the Treasury of the Three Magi, in the great “Dom,” or Cathedral at Cologne. Some of these gems are nearly two inches long. In our own land beautiful specimens can be seen in the Morgan collection at the American Museum of Natural History and in the Higinbotham Hall in the Field Museum of Natural History, Chicago, Illinois. Pliny quotes from Juba the tradition that the topaz (chrysolite) derived its name from the Island of Topazos, in the Red Sea, the first specimen having been brought thence by the procurator Philemon, to Berenice, mother of Ptolemy II, Philadelphus. This monarch is said to have had a statue of his wife Arsinoë made from the stone.[67] If there be any foundation for this latter statement, the precious gift sent by Philemon must have been a mass of fluorspar, or some similar material. More than three hundred years after Pliny’s time, Epiphanius, evidently repeating another version of this tradition, states that the “topaz” was set in the diadem of the “Theban queen.” Chrysolite (olivine, peridot), to exert its full power, required to be set in gold; worn in this way it dispelled the vague terrors of the night. If, however, it were to be used as a protection from the wiles of evil spirits, the stone had to be pierced and strung on the hair of an ass and then attached to the left arm.[68] The belief in the virtue of the chrysolite to dissolve enchantments and to put evil spirits to flight was probably due to the association of the stone with the sun, before whose life-giving rays darkness and all the powers of darkness were driven away. Chrysoprase