DIAMONDS.

Thames Star, Volume XIV, Issue 4516, 26 June 1883, Page 2

DIAMONDS.

Diamond, (a corruption of adamant) is the most highly prized of all gems, though in former times, before the method of catting was known, it was regarded as inferior to the more highly- coloured stones. Diamonds are at present found mainly in Brazil, South Africa, and Australia. The famous mines at Golconda and Bundelcund in India now yield very few stones. Diamonds have been fonnd embedded in micaceous quartzose rock termed itacotwm.itc, but they usually occur in alluvial deposits— i.e., in sand and gravel—from which they arc extracted by washing and picking. They are found ; crystalised in octohedrons, or in forms derived from octohedron. the faces of the crystals being frequently curved, bat they are also very often met with in rounded forma. In Brazil, darkI coloured diamonds, termed carbonado, | occuif in small pebbles. The diamond is the hardest substance known, and has a very high refractive power; hence the brilliant 1 effect when a properly cut stone is exposed to light. Colourless stones, or stones of the first water, as they are termed, are the most highly prized, those with a brownish tinge being much less valuable. Diamonds of a beautiful rose, blue, or, green colour have also been found ; but these are very rare, and are consequently - extremely valuable. The Hope diamond is of a beautiful blue color. To increase the brilliancy of the diamond,, it undergoes the process of cutting. This is a difficult and tedious operation, requiring much labor and skill. It is effected by the aid of a revolving metallic wheel coated with diamond dust moistened with oil. No substance except diamond dust is sufficiently hard for this .purpose. The out and polished surfaces are termed facets, and the number, shape, arrangement, &c, of the facets depend on the size and shape of the stone, and on the purpose for which it is to be used.