Another gem held in high estimation by the ancients was the emerald,[840] the exquisite colour of which, generally the most intense green, was supposed to be more grateful to the eye than the sight of vernal woods or meadows. For this reason many persons selected it for seals in preference to all other stones.[841] Even the lapidaries employed in cutting it were believed to have their vision improved by its refreshing virtues. All emeralds, however, are not of one hue, but exhibit every possible shade of green, from the dusky tint of the olive leaf to the pale verdure of the acacia.[842] The Greek jewellers appear to have judged of the genuineness of this stone by plunging it into clear water: for if it were a true emerald it would, they thought, impart its colour to the whole of the surrounding element; if not, a small part only of it would be tinged.[843] ----- Footnote 840: Plin. xxxvii. 16. Boetius, l. ii. c. lii. 195. Menand. ap. Athen. iii. 46. Luc. Saturn. Epist. § 29. Suid. v. σμάραγδος. t. ii. p. 769. a. Footnote 841: Theoph. de Lapid. § 24. Footnote 842: See Baldæus, description of the Coasts of Malabar and Coromandel, chap. xxiv. Footnote 843: Theoph. de Lapid. § 23. ----- The ancients possessed a species of bastard emerald, found in vast blocks, so that we read of an emerald obelisk in Egypt, which, though consisting of but four pieces, rose to the height of sixty feet.[844] Of this stone, probably, was the famous pillar which adorned the entrance of the temple of Heracles at Tyre.[845] Of real emeralds the largest known does not exceed six inches in length, and two in diameter. It may be observed, that much pains and labour were expended in bringing the emerald to its lustre.[846] ----- Footnote 844: Id. § 24. Plin. xxxvii. 19. Footnote 845: Theoph. de Lapid. § 25. Footnote 846: Id. § 27, seq. ----- The lyncurios or modern hyacinth is enumerated among the seal gems.[847] Its colour is that of flame with an intermixture of deep red, though it is sometimes found of a full saffron hue, or even resembling amber. It has by several writers been supposed to be the tourmaline. The lyncurios was exceedingly hard and difficult to work. They likewise cut and engraved for seals the amber, which Theophrastus describes as a native mineral; the hyaloides, the omphax, the crystal,[848] the sardonyx, the agate, the onyx, and the amethyst.[849] A gem of extraordinary beauty was once found in the gold mines of Lampsacos, which, having been engraved by a Tyrian lapidary, was presented to the Persian King.[850] ----- Footnote 847: Anselm. Boet. Gem. et Lapid. Hist. l. ii. c. 258, p. 477. Footnote 848: Winkelm. ii. 110. Footnote 849: Theoph. de Lapid. § 30. Poll. iii. 87. Luc. Dial. Meret. ix. § 2. Cf. de Syr. Dea, § 32. Precious stones of various kinds were employed to represent the eyes in statues, when the white was imitated by thin silver plates. Winkelm. Hist. de l’Art. t. ii. p. 94.