The massive and opaque varieties known as adamantine spar are said to be found in granitic rocks in China, and on the coast of Malabar; but very little is known concerning the exact condition of these localities. Fibrolite and magnetic iron are said to accompany the corundum in several of its localities. Brard believes that the blue diamond of Pliny of the Island of Cyprus is no other than the blue sapphire. And this belief is not without foundation, as some of the varieties of corundum are found on the islands and coasts not far distant. Occasionally stones of fine blue tints and of considerable size are found. In 1853, a large and beautiful piece was found in the gem strata near Ratnapoora, and sold to a Moor at Colombo for $20,000. Fragments as large as goose eggs are also sometimes found in the Saffragan district, but are of an inferior character, according to Dr. Davy. Mawe describes one of three hundred and ten karats. We have in our collection a transparent, light-blue, and finely shaped crystal of three hundred and eight karats, but we fear that it will not match the distinct crystal of three inches in length which belonged to Sir Abram Hume. The suite of blues exhibited by this gem is very extensive, and embraces all known shades and even the purest prismatic hue. The deep regal blue is too intense a color for a night gem, as by artificial light it becomes black. But there are sapphires of a celestial blue possessing perfect limpidity and rich velvety reflections that retain their splendid colors by night as well as by day, and they merit the distinction bestowed upon them by the ancients when they consecrated them to Jupiter. These superb gems are, however, exceedingly rare, and are eagerly sought for by amateurs at prices far above that of the colorless diamond. The general color of the blue sapphire is a light shade, from which it passes through various gradations to a blue black. Perfect stones of fine colors are quite rare, for they are apt to be clouded, and the color distributed unevenly in the mass. Frequently the color is in one extremity of the crystal, or appears as a spot on the surface of a nodule. In other specimens it is arranged in bands or thin clouds. Hence much skill is often required to cut them so that the gem may display a proper distribution. Frequently the color is left in the bottom of the gem, and when the stone is set the color is diffused by refraction through the upper portions, so as to give the gem the appearance of being colored throughout.