The process of reduction by this means is very rapidly accomplished by the skilful workman. At a glance he ascertains the direction of the laminæ, which remind one of the layers of the onion, and then cuts a small notch with another diamond in the place he selects. In this minute rift he places the edge of his blunt steel knife, and, tapping the back of it with a light iron rod, the diamond is split with perfect ease. By this process flaws and imperfections in the external layers of the stone are removed without delay. In reducing the natural diamond to a regular form much of its substance is lost, and sometimes as much as one half of the weight of the stone. This loss, however, depends greatly upon the natural form of the crystal. The perfect octahedrons lose but one fifth of their weight when transformed into the shape of the brilliant; but the rhombohedrons lose over one third in taking the same form. The following will give the reader an idea of the losses of the rough stones when converted into fine gems. However, it must be remembered that these great stones are generally of irregular shape and are rarely of fine crystalline forms. The Mogul weighed in the rough 780¹⁄₂ karats, but was reduced in cutting to 279⁹⁄₁₆ karats. The Regent weighed 410 karats, reduced to 136¹⁴⁄₁₆ karats. The Koh-i-noor weighed 186¹⁄₂ karats, reduced to 102¹⁄₂. L’Etoile du Sud, 254¹⁄₂ karats, reduced to 124⁴⁄₁₆. The process of cutting diamonds of large size is always attended with risk, and is necessarily a costly operation. The Regent cost in cutting $25,000, and occupied two years’ time. The Star of the South, which was cut by Coster, occupied but ninety days, and the Koh-i-noor only thirty-eight working days. This great feat in diamond-cutting was performed by the ablest of the Holland lapidaries, with the aid of steam power. Although the time expended was less than forty days, yet the cost of cutting is said to have been $40,000, which sum was lessened by the sale of the rifted fragments. The Oriental lapidaries, destitute of mechanical appliances of any considerable aid, consumed years in cutting some of the paragons of India. This condition of affairs will explain the reason why the Armenian lapidaries asked the immense sum of $80,000 to cut the slab of diamond weighing 130 karats, which was captured by the Sultan of Persia at Coocha, in 1832. The process of diamond-cutting has within a few years been established in the United States, and is due to the energy and superior inventive talent of Mr. Henry D. Morse, of Boston. This gentleman conceived the idea of arranging a machine for the cutting and polishing of these gems, to enable the American jewellers to have their work performed at home, instead of sending it to Europe.