a precious stone belonging to the genus of siliceous earth. The word is derived, according to some, from the French smaragde, and that from the Latin smaragdus, signifying the same thing; by others it is said to be derived from the Italian smaraldo, or the Arabian azmorad. According to Cronstedt the emerald is the softest of all the precious stones, though other naturalists place it the next after the diamond in this respect. It is perhaps the most beautiful of all the gems, and, according to Wallerius, when heated in the fire, changes its colour to a deep blue, and becomes phosphorescent; but recovers its green colour when cold. When pulverized it has a white appearance, and, with borax, melts to a very thin and colourless glass. It becomes electric by being rubbed, and some have the property of the tourmalin, viz. of being electrified by heat, and in that state attracting ashes or other light substances; though the emeralds are less powerful than the tourmalin, and after having attracted the ashes, they retain them without any signs of repulsion.

Pliny mentions twelve different kinds of these precious stones; though it appears, from the vast size of some of them, that they must have been only certain kinds of green spar, or other green stone, which at that time Emerald time went under the name of emerald among the ancients. The true emerald is found only in very small crystals, from the size of 1/6th of an inch in diameter to that of a walnut. Theophrastus, however, mentions one four cubits long and three broad; likewise an obelisk composed of only four emeralds, the whole length being 40 cubits, and the breadth from four to two.

Engestroom informs us, that the emeralds, in their rough or native state, consist of hexagonal columns mostly truncated at both ends; and that he had some in his possession, which in a gentle heat became colourless, but in a strong heat white and opaque, without any mark of fusion. Brunick distinguishes them into two classes. 1. The pale green emerald, which comes from the east and from Peru, the figure being that of an hexagonal truncated prism, and the basis a vein of white quartz. 2. The dark green emerald, which is also columnar, but very dark coloured, striped longitudinally, and has little transparency. The points are generally broken off longitudinally, though Davila mentions one resembling a blunt triangular pyramid; and in the imperial cabinet at Vienna there is one with a five-sided pyramid. These are the emeralds which become electrical by heat; though all of them do not; and those which do so cannot be known but by actual experiment. The finest specimen of the former kind of emeralds is to be seen in the treasury of the holy chapel of Loreto, containing upwards of 100 of these precious stones great and small. A fellow to this was made by art, and both were presents to the king of Sicily, designed to represent two Mount Calvaries.

Emeralds are distinguished by the jewellers into two kinds the oriental and occidental. The true oriental emerald is very scarce, and at present only found in the kingdom of Cambay. So great indeed is the scarcity of them, that an opinion prevailed that there are no oriental emeralds. This opinion is adopted, among others, by Mr. Bruce; who informs us, that he made an excursion to the island of emeralds in the Red sea, and endeavours to show that there never were any emeralds but what came from America, and that those said to have been found in the East Indies were imported from that continent. It is probable, indeed, that in former times any kind of crystal tinged of a green colour might be called an emerald, and hence the green cockle spar brought from Egypt may have obtained the name of mother of emeralds; but of late some emeralds have been brought from Cambay into Italy, which greatly excelled those of America. The best emeralds of the western continent come from Peru, and are called oriental by the jewellers: some are found in Europe, principally in the duchy of Silesia in Germany.

Rough Emeralds.—Those of the first and coarsest sort, called plasmes, for grinding, are worth 27 shillings sterling the marc, or 8 ounces. The demi-morillons, 8l. sterling per marc. Good morillons, which are only little pieces, but of fine colour, from 2l. to 15l. per marc. Emeralds, larger than morillons, and called of the third colour or sort, are valued at from 50l. to 60l. the marc. Emeralds, called of the second sort, which are in larger and finer pieces than the preceding, are worth from 65l. to 75l. per marc. Lastly, those of the first colour, otherwise called negres cartes, are worth from 110l. to 115l.

Emeralds ready cut, or polished and not cut, being of good stone, and a fine colour, are worth—

| Carats | Value | |--------|-------| | One | 0 | | Two | 1 | | Three | 2 | | Four | 3 | | Five | 4 | | Six | 5 | | Seven | 6 | | Eight | 7 | | Nine | 8 | | Ten | 9 |

To counterfeit Emeralds: Take of natural crystal, four ounces; of red lead, four ounces; verdigris, forty-eight grains; crocus martis, prepared with vinegar, eight grains: let the whole be finely pulverized and sifted: put this into a crucible, leaving one inch empty: lute it well, and put it into a potter's furnace, and let it stand there as long as they do their pots. When cold, break the crucible; and you will find a matter of a fine emerald colour, which, after it is cut and set in gold, will surpass in beauty an oriental emerald.