exhibit a decided red color they form the most gorgeous of gems. The largest and finest of this description known is the ten-karat stone purchased by the Emperor Paul of Russia for one hundred thousand roubles. This gem may be considered the marvel of the mineral kingdom. The princely collection of the late Mr. Hope possessed one of a blood-red garnet shade, also a fine twelve and a half karat stone of an apricot hue, besides several others of a beautiful hyacinth red, or of a lilac pink. The celebrated cabinet of gems belonging to the late Marquis de Drée contained a large and beautiful rose-colored diamond. Prince Riccia, of Naples, acquired in 1830 a very fine rose-colored brilliant of fifteen karats weight. M. Halpen, in 1838, exhibited a magnificent gem of this description of twenty-two and a half karats. Among the crown jewels of France there are several splendid brilliants of a peach-blossom hue, and there are also quite a number to be seen among the princely caskets of Europe. It is, however, somewhat remarkable that this gem, although possessing several shades of red, never, or very rarely, occurs of a decided violet or purple color. Diamonds of a light aqua-marine of greenish and bluish tints are not rare, but those of a positive grass-green color are uncommon. Perfect stones of decided green form the most magnificent gems of this color. The velvety green flashed forth by the extraordinary power of the stone surpasses beyond comparison the finest emeralds with their duller reflections. In fact, we may term the splendid green diamond of forty karats, now in the Green Vaults at Dresden, as being one of the five paragons among all the gems of the world. In the Museum of Natural History in Paris there are some small diamonds of very fine shades of green, which were collected by the celebrated Werner. Some of the diamonds which have a slight milky hue, when cut so as to allow the play of light within the stone, present a very beautiful appearance. The varied flashes of colored rays, in contrast with the duller hues of the stone, appear like the charming effects of the finest specimens of Siberian adularia, and are therefore entitled to the name of aventurine diamonds. The asterism, or star-like form of six rays, which is so beautifully displayed by the sapphire when it assumes a certain form of internal arrangement of crystallization, is sometimes, though very rarely, witnessed in the diamond. There is one of this description to be seen in the Museum of the _Jardin des Plantes_ in Paris.