The Hindoos are the best buyers of gems of all the nations of the world. Their rajahs and princes pay the highest prices for the paragons; and the poor native had rather invest in a gem, which to his simple belief adds to his security and happiness, than hoard gold coins, which are no better for concealment. The Moors are also generally the lapidaries. The tools which they use in cutting the gems are rude and primitive, and often the stones are much impaired under their hands; but some of the workmen are skilful and are able to copy with exactness the most perfectly cut gems of the European lapidaries. Workmen of the inferior class may be found in the little towns all over the island; but the artists of the first rank are located at Callatura and Colombo. Immense numbers of garnets, zircons, and inferior sapphires, with other gems, are cut by these rude artisans, who place but little value on their time, and therefore work for a trifle. These precious stones are then sold on the island or exported to foreign lands, but are generally taken to India by travelling merchants, who exchange them for produce or money. The demand is so great from the populous Mohammedan nations, that many of these gems are really higher in price in India than in the gem marts in Europe, as in the time of Tavernier, three hundred years ago. Another potent reason prevents the market from being glutted: the Hindoo parts with his gem reluctantly, and only in case of necessity or in hope of greater gain; and the wealthy Parsee prides himself upon his display of gems, as well as upon his degree of caste. The quantity of gems treasured up by the inhabitants of India must be immense. The composition of the sapphire, when found in the clear, transparent form, is pure alumina. Its degree of hardness is 9, being inferior only to the diamond; and its range of colors is very extensive, embracing most of those seen in the solar spectrum. Its specific gravity varies from 3.9 to 4.3; and, with the exception of the zircon, it is the heaviest of all the gems. It is also compact and exceedingly tough in its texture, and resists the shocks and wear of time better than any other gem, not excepting even the diamond, which is harder, but far more fragile. In point of brilliancy, it is below the zircon, garnet, and the spinel, its refractive index being 1.77 to 1.79. This mineral possesses remarkable electrical properties, but not so marked in degree as in the tourmaline or topaz; when this property is excited in the polished specimen, the attraction continues for a considerable length of time. The property of double refraction is not often very distinct, and by means of this peculiarity it is sometimes detected from the spinel.