In the French casket of gems, in the year 1791, mention was made of a superb yellow sapphire of 27¹⁴⁄₁₆ karats, two of 13 karats each, and one of 11 karats, all of which were valued at 8,900 francs. The beautiful specimen now exhibited in the Cabinet of Minerals, in the Garden of Plants at Paris, which is of the purest and richest color, joined with wonderful lustre, is supposed to be the gem mentioned above among the crown jewels. The French amateur and writer on gems, Caire, once possessed a remarkable and charming yellow sapphire of the great weight of twenty-nine karats. Its former Hindoo owner had seriously impaired its beauty by drilling a hole in one extremity for the purpose of suspension; and had also engraved on its sides inscriptions in Arabic, which were probably condensed quotations from the Koran to preserve the possessor from harm. The green variety is probably the rarest of all the forms of sapphire, and finely tinted stones are very seldom seen. They are generally of a faint sea-green tinge, and resemble beryls in their hues. But when they do occur of grass-green color, they form magnificent gems and far exceed the true emerald in lustre and brilliancy. We very much doubt, however, if they ever approach the emerald in its exquisite shade of green. We have examined many green stones from the Ceylon gem mines, and with one exception have found them to be green spinels, zircons, and tourmalines of various intensities of shade. The one undoubted specimen referred to was of an impure hue. The celebrated Romè de L’Isle possessed two beautiful crystals of green sapphire. When they display the sea-green hue or the mountain-blue of the beryl, they are then called Oriental aqua-marines, but fine stones of this description are not common. We have seen some small but very beautifully tinted gems of this class from the gold fields of Montana. Barbot speaks with ecstasy of two green sapphires from Matura in Ceylon, and which far exceeded any other gem in their velvety color, limpidity, and brilliancy. It is possible that these two gems may have been zircons, as these stones abound in Matura, and are of the most vivid lustre when perfect. But stones of fine green hues of this mineral are exceedingly rare. We have also seen a specimen of transparent corundum from Siam which was dichroite, blue and green one way, and entirely green the other. It called to mind that found at Expailly in France, by the naturalist Fanjas, and which appeared of an almost emerald green when viewed in one direction, or of a most beautiful blue when the axis of vision was changed.