Brazil was not regarded as a diamond-yielding country until 1727, when the true nature of certain crystals found in the gold washings of the province of Minas Geraes was first detected. Diamonds occur not only in this province, but in Bahia, Goyaz, Matto Grosso, and Paraná. The geological conditions under which the mineral occurs have of late years been carefully studied by Professors Derby, Gorceix, and Chatrian. The diamonds are found in the sands and gravels of river-beds, associated with alluvial gold, specular iron ore, rutile, anatase, topaz, and tourmaline. In 1853 an extraordinary diamond was found by a negress in the river Bogagem, in Minas Geraes. It weighed 254-1/2 carats, and was cut into a brilliant of perfect water, weighing 125 carats. This brilliant, known as the 'Star of the South,' was sold to the Gaikwar of Baroda for £80,000. Both the Indian and the Brazilian diamond-fields have of late years been eclipsed by the remarkable discoveries of South Africa. Although it was known in the last century that diamonds occurred in certain parts of South Africa, the fact was forgotten, and when in 1867 they were found near Hopetown, the discovery came upon the world as a surprise. A traveller named O'Reilly had rested himself at a farm in the Hopetown district, when his host, a man named Niekerk, brought him some nice-looking stones which he had got from the river. O'Reilly, when examining the pebbles, saw a diamond, which afterwards realised £500. Niekerk afterwards bought a diamond from a native for £400 which realised £10,000. The principal mines are situated in Griqualand West, but diamonds are also worked in the Orange River Free State, as at Jagersfontein. The stones were first procured from the 'river diggings' in the Vaal and Orange rivers. These sources have occasionally yielded large stones; one found in 1872 at Waldeck's Plant on the Vaal weighed 288-3/8 carats, and yielded a fine pale yellow brilliant, known as the 'Stewart.' [Illustration: Kimberley Diamond-mine.]