THE DIAMOND AND OTHER PRECIOUS STONES. 353 



With US the word carbuncle is little used except to describe a ruby of 

 cousidcrable size. Pliny has evidently confounded the Indian ruby with 

 the garnet, which is found everywhere. Certain rubies cut spherically — 

 a form which is called calotte spheriqiie, tallow drop, or cabochon — pre- 

 sent in the middle of their red tint a white six-rayed star, which changes 

 with the i)osition of the eye and forms in the sunlight a beautiful spec- 

 tacle. This effect is called asterie. It is found also in the sapphire, a 

 near relation of the ruby; like it, being composed of aluminium, and 

 colored by iron, differing only in its color, Vvhich is blue, while that of 

 the ruby is the most vivid and purest red. 



Xext in rank to the ruby we place the emerald^ of which Pliny says 

 no gem has a color so agreeable. This stone, which comes to us from 

 Peru and New Grenada, is very soft, hardly scratching rock-crystal. It 

 is found in beautiful green crystals, implanted and produced in a kind 

 of freestone of a whitish color; and we can comprehend no cause other 

 than electricity for such a deposit as that of the emerald in the midst 

 of a stone differing both in nature and in color from this gem. Nero, 

 who was near-sighted, used an emerald, hollowed on both sides, 

 through which to look at the games in the amphitheaters. This was 

 doubtless the first approach to spectacles, since this invention does not 

 date very far back. 



The emerald, like the ruby, is a six-sided prism and squarely cut at 

 the ends. This stone is very light, losing in water more than one-third 

 of its weight. Its tint is so lovely that we overlook its want of hard- 

 ness, which might properly almost exclude it from the rank of distin- 

 guished gems. At the time of the conquest of Peru a magnificent 

 emerald was sent in homage to the Pope ; and several years afterward 

 the emerald mines there were said to be exhausted or lost. About 

 twenty years ago the principal of a large establishment in Paris, M. 

 Mention, received from South America some magnificent specimens, 

 which quite revived the emerald trade, continued since without inter- 

 ruption by Charles Achard. The deeper the hue of the emerald the 

 more it is esteemed. It is the largest end of the crystal that is the most 

 strongly colored. The emerald loses none of its brilliance in artificial 

 light ; a valuable property in our modern society, where all great re- 

 unions are held at night. Haiiy includes in the emerald family the 

 aquamarine and the ber^d, one of a greenish blue, the other yellow, 

 but both being like the emerald in form and chemical compo.'?ition. 



The emerald, as well as all stones whose color we wish to develop, 

 should be cat with a flat upper surface, surrounded by retreating facets, 

 continued all the way underneath. The orientals cut them in broad 

 thin plates, which, apparently, ought to show the colors of the stone to 

 the best advantage ; but the reflection of white light from the large 

 upper surface becoming mingled with that which traverses the gem, 

 renders the hues of the latter less discernible. This is the reason why 

 they are not cut with a table and surrounded by facets; for thiTO in 

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