TFIE DIAMOND AND OTHER PRECIOUS STONES. 35? 



in liis book on the Political Economy of the Romans, is about 4,000,000 

 francs. Now, if we recollect that before diamond-cutting was under- 

 stood, the opal was the only stone which, receiving the white light of 

 day, gave it back refracted in a thousand magic tints, this price does 

 not appear too much for a gem which was the Koh-i-noor or the Regent 

 of Rome. The opal, at the same time that it is the lightest of all gems, 

 losiug in water one-half its weight, is also one of the softest. Those of 

 India are somewhat superior in these respects. 



In actual value the Paris market places, next after the opal, two 

 stones of an undecided greenish yellow, viz, the chrysolite and the peridot. 

 The first is characterized by its lively luster, its polish, analogous to 

 that of the sapphire, and its warm bright tint. It is the " stone of affec- 

 tion" of Sir David Brewster, so celebrated for his researches in optics. 

 The chrysolite^ or Cymophane, has often the milkiness of the sapphire. To 

 enumerate its other properties we must enter the broad field of modern 

 optics, speak of double refractiou, of polarization, and the colors wliicli 

 are exhibited in the light which traverses crystals, and finally of the 

 three kinds of colored rings, namely, those with black lines, those with 

 black crosses, and those without either lines or crosses. The rings in 

 the chrysolite, as in the topaz, are of the first kind. This is not, however, 

 a distinguishing j)roperty, since it can be made to appear, with a little 

 dexterity, in almost all cut stones. As to the peridot^ or olivine, its color 

 is deeper than that of the chrysolite ; it is always of a greenish olive, 

 mingled with yellow, the green predominating; is very soft, scarcely 

 scratches glass. Its lack of hardness gives an appearance of dullness 

 to its edges. The peridot, which comes to us from India, is there used 

 as ornaments of harness, as well as are the flatl}' cut emeralds of the 

 same country. Ceylon, which is above all other places distinguished 

 for the production of colored stones, does not continue to furnish the 

 peridot, which, however, is not rare in the lava from volcanos, although 

 the specimens are too minute to be worthy of the art of the lapidary. 



I have often seen in the possession of an amateur interesting collections 

 of these small crystals, which, viewed by lamplight and under a micro- 

 scope, verified ail the crystallographic laws of Haiiy. A crystal of a 

 peculiar i^roperty, though of the minutest dimensions, was to this eccen- 

 tric amateur what the Star of the South would be to an ordinary" collector 

 of diamonds. His long and minute investigations gave him great facil- 

 ity in the study of minute gems. From a stone covered with small crys- 

 tals he would select one which, under the microscope, and properly 

 lighted, would present the most interesting scientific indications. 



The j)enV/o# has the distinguished honor to be the only precious stone 

 that has thus far been found in aerolites falling from the sky, although 

 these little olive stones are of no great value if sold by the carat; but if 

 suitably cat in their matrix, they afford, if not very beautiful, certainly 

 very curious, specimens. I need scarcely say that the existence of a 

 crystallized stone found in bodies falling from the atmosi>liere refutes the 



