Note 3013 — BOOK XXXVII. THE NATURAL HISTORY OF PRECIOUS STONES.

“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.