79. COMMON AMETHYST.—_This is a violet─coloured crystal_, which acquires considerable brilliancy in polishing, and is sometimes of sufficient size to be formed into columns more than a foot in height, and several inches in diameter. When the colour is good, and uniformly diffused, amethysts are cut into necklaces, bracelets, ear─rings, and seals; and, when less pure, they are manufactured into snuff─boxes. They are valued in proportion to the depth of their colour, and to their perfect transparency. The most favourite form in which they are made up is in necklaces; and as it is not easy to find a number of perfect stones with precisely the same tint of colour, necklaces of this description are very valuable. The finest that is known was in the possession of her late Majesty. When the colour is not uniformly diffused, jewellers sometimes expose amethysts, for a little while, in a mixture of sand and iron─filings, to a moderate heat; and, by this process, their appearance is rendered more uniform. The amethyst being almost the only coloured stone that can be worn with mourning, it derives, from this circumstance, a considerable addition of value. This species of gem was well known to the ancient Greeks and Romans, and was held by them in great esteem. Its name is derived from the Greek language, and implies a power of preventing intoxication; which (originating no doubt in the resemblance of its colour to that of wine, and the absurd doctrine of sympathies) it was believed by the ancients to possess. They ascribed to it many other virtues, equally surprising and equally absurd; particularly that the wearing of it would expel melancholy, procure the confidence and friendship of princes, render people happy, and even dispel storms of wind and hail. The ancients frequently engraved upon amethyst; and their favourite subject was the representation of Bacchus and his followers. The most valuable amethysts are imported into Europe from India and Ceylon. These, although they are with truth denominated oriental, must be carefully distinguished from the true oriental amethyst (55), which is a much more valuable gem. The amethysts next in esteem are found in Brazil, and are procured in the mining districts of that country. Siberia, and various countries in Europe, especially Germany and Spain, also furnish very beautiful amethysts; and inferior stones of this description are even found in the mountainous districts of some parts both of Scotland and Ireland. 80. FALSE RUBY _is a crystal of red colour_, and found in Bohemia, Silesia, and Barbary. 81. FALSE, _or_ WATER SAPPHIRE _is a blue crystal_, which does not differ much in appearance from the true sapphire, but is considerably less hard. This kind is found in Bohemia, Silesia, and some parts of Switzerland, but it is not so valuable as the last. 82. FALSE EMERALD _is a green variety of crystal_, the scarcest and most valuable of all the coloured kinds. It is chiefly found in Saxony and Dauphiny.