DIAMOND: COLOUR 135 



that of the yellowish-green of uranium glass, but inclining more to yellow, is mentioned by 

 Boutan. 



The ten-carat ruby-red stone, which belonged to Czar Paul I. of Russia, and which 

 IS said to be still preserved with the Russian crown jewels, is often mentioned as an 

 example of a red diamond ; nothing more definite concerning it is, however, known. A 

 better authenticated example is the " Red Halphen "diamond, a ruby-red brilliant weighing 

 one carat; while recently Streeter has reported the discovery of a beautiful red stone in 

 Borneo, and its sale in Paris. Several examples of beautifully transparent rose-red diamonds 

 are known ; such, for instance, as that of the fifteen-carat stone belonging to the Prince of 

 Riccia, a few smaller specimens in the treasury at Dresden, and a thirty-two-carat stone, the 

 most beautiful rose-red known, in the treasury of Vienna. A rose-coloured brilliant, called 

 the " Fleur de pecher," is among the French crown jewels, and Tschudi mentions a peach- 

 blossom-red stone from the Rio do Bagagem, in Minas Geraes, Brazil. 



Blue diamonds are the rarest of all. A magnificent blue brilliant of 44^ carats, the 

 " pearl of coloured diamonds," was formerly in the possession of Mr. Hope, a London 

 banker. It is probably a portion of Tavernier's blue diamond of 67^ carats, stolen in 1792 

 with the French crown jewels. A small diamond of a deep blue colour, and a pale blue one 

 of forty carats, are preserved in the Munich treasury. 



Black diamonds perhaps deserve a brief mention. Crystals of a uniform black colour 

 have been found in Borneo, and also very rarely in South Africa. The opacity of such 

 stones, combined with their high degree of lustre, almost metallic in its character, render 

 them, when cut, of peculiar beauty, and well suited for use in mourning jewellery. These 

 crystals of black diamond must not be confused with the black carbonado of Brazil, 

 to be described later. A few brown stones of a delicate and beautiful coffee shade are 

 known ; these also come from Brazil. 



As is almost always the case with precious stones and other minerals, the colour of 

 which is due to enclosed foreign matter in an extremely fine state of division, so also in the 

 diamond the distribution of the colouring-matter is not always perfectly uniform throughout 

 its whole mass. The pigment may be collected or accumulated in isolated patches, while 

 the rest of the stone is either colourless or less deeply coloured. In numerous cases, only the 

 thin surface layer of the crystal is coloured, the interior of the stone being colourless ; this 

 occurs often in Brazilian stones, especially those from the Rio Pardo, in the Diamantina 

 district. When the outer layer, which is often pale green in colour, is removed in the 

 process of cutting, a perfectly colourless stone is obtained. Tschudi mentions a fine emerald- 

 green brilliant from Brazil, which before cutting had a sooty black appearance ; another 

 specimen of similar appearance retained its black colour almost entirely after cutting, a few 

 facets only appearing white. 



Not infrequently the bulk of a rough diamond is colourless, the edges and corners only 

 being coloured ; many Brazilian stones are of this description, as well as specimens from 

 South Africa, including some of the " smoky stones " already mentioned. In these the deep 

 smoky-grey colour is sometimes confined to the corners of the stone, the interior being faintly 

 coloured or entirely colourless ; a stone so coloured is desciibed as a " glassy stone with 

 smoky corners.'" Diamonds in which these conditions are reversed also occur, the edges and 

 corners being colourless, and the central portion coloured. 



Sometimes, though rarely, a stone shows two differently coloured portions ; the two 

 portions of one mentioned by Mawe were coloured respectively yellow and blue. Stones 

 showing a number of differently coloured sectors, sharply separated from each other, and 

 radiating from a central point, are also of rare occurrence. Thus smoke-grey and colourless 



