[Fr., from Gk. adamanlos."] The hardest and next to the ruby the most valuable of gems. Chemically, it is pure, crystallized carbon, its crystalline form belonging to the regular or cubic system, having henerally eight or twelve faces. The best diamonds are perfectly clear and colorless, and are described as being ofthe first water. The peculiar lustre of the diamond distinguishes it from all other sub-stances, and the vivid brightness and intense glow of its reflections are unsurpassed by any other stone. It is also distinguished from other gems by its extreme hardness. The value of a diamond is greatly enhanced by cutting. This industry was at one time confined almost exclusively to Amsterdam, but it is now carried on in other places. Diamonds are cut in two forms - the brilliant and the rose cut. The former brings out better the beauty of the stone. The dust is used by the lapidary and the gem-engraver, and the stone is used for jewelling watches and in cutting glass, and for the latter purpose it must not be cut. Inferior sorts are used by engineers in rock-boring, and by copper-plate engravers as etching-points. Diamonds are found in India and Borneo, and sometimes in North America and Australia; but the chief diamond fields of the present day arc those of South Africa and Brazil. They were first discovered in South Africa in 1867, existing there in a blueish earth, from which they are washed out. An immense number of diamonds, of great collective value, have been obtained from these mines. Among the large diamonds found the most famous is the Koh-i-noor, which has a very interesting history. Others are the Great Mogul, the Orloff, the Regent, and the Sancy.
THE ORLOFF DIAMOND.