[3011] The emerald is supposed to derive this colour from a minute portion of oxide of chrome.
[3012] Engraved emeralds are but seldom found among collections of ancient gems. In 1593, there was one found in the tomb of Maria, daughter of Stilicho, in the Vatican, with the head of Honorius, her husband, engraved upon it.
[3013] “It may here be objected that real emeralds are too small to admit of being used as mirrors; but the ancients speak of some sufficiently large for that purpose, and also of artificial ones; so that we may with certainty conclude, that they classed among the emeralds fluor spar, green vitrified lava, or the green Icelandic agate, as it is called, green jasper, and also green glass.”—Beckmann, Hist. Inv. Vol. II. p. 67. Bohn’s Edition. It has also been suggested, with reference to this passage, that Nero was short-sighted, and that this emerald was formed like a concave lens. The passage, however, will hardly support such a construction. Ajasson thinks that it must have been a Dioptase or Siberian emerald; or else a green Corundum.
[3014] Ajasson is of opinion that the Dioptase, Siberian emerald, or Malachite emerald is meant.
[3015] Ajasson thinks that this may be the Dioptase or Achirite of Chinese Bucharia; and that the merchant Achir Mahmed, from whom it takes its name, was by no means the first to introduce it, or to circulate his wonderful stories as to its formation.
[3016] See B. ii. cc. 47, 48, and B. xviii. c. 74.
[3017] Mount Zalora. in Upper Egypt, still produces emeralds, and was probably the only locality of the genuine stone that was known to the ancients.
[3018] “Cetarias.”
[3019] Ajasson remarks that the greater part of the defects here described belong in reality to the Dioptase.
[3020] “Sal.” See Chapters [8], [10], [22], and [37], of this Book.