80 
Transactions of the Royal Society of South A frica. 
Year. 
Stones not brown. 
Cleavages not brown. 
1901 
1902 
1903 
1904 
1905 
1906 
1907 
1908 
1909 
1910 
1911 
1912 
1913 
1914-16 
Per cent. 
24-53 
23- 32 
22-83 
21- 24 
22- 49 
22- 04 
24- 16 
23- 66 
23-28 
23-64 
22-42 
22-28 
21-15 
21-26 
Per cent. 
1013 
10-61 
10- 64 
11- 01 
11- 76 
12- 35 
1402 
14-25 
14-02 
14-77 
13- 79 
14- 74 
14-63 
12-92 
Here we see that there has, apparently, also been a disposition for these 
whiter diamonds to break up more freely at the greater depths, although 
not to the same extent as in the case of the brown diamonds. For whereas 
in the five years 1899-1903 67 per cent, of^ all brown diamonds was brown 
cleavage, in the five years 1909-13 the cleavages had increased to 84 per 
cent., an increase of 17 per cent., the corresponding percentages for diamonds 
other tlian brown being 29 and 39, an increase of 10 per cent. Moreover, 
in absolute numbers, the chances preponderate that a brown diamond 
will be a cleavage, whereas the odds are quite the other way when the 
diamond is not brown. There is pretty well as much brown cleavage as 
there is cleavage not brown ; the stones other than brown outnumber the 
brown stones by ten to one. Bauer, in one of his characteristic inaccuracies, 
has stated that in the case of Cape diamonds " it is a remarkable fact that 
these cleavage fragments are nearly always white — that is, colourless, or, at 
least, very faintly coloured ; fragments of a dark colour, or of a decided 
yellow, are extremely rare, so that we must conclude that such stones offered 
greater resistance to fracture than did the colourless diamonds" (p. 209). 
The above statistics show just the opposite — that it is the colourless dia- 
monds rather which resist fracture, as compared with brown, at any rate, 
although, as we shall see when we come to speak of Pool and Dutoitspan 
diamonds, yellow diamonds are perhaps more resistant than white. Apart 
from any question as to the influence of colour upon the cohesion of a 
diamond, we should naturally expect cleavages to appear somewhat lighter 
in colour than stones, for the same reason that many cut diamonds appear 
lighter in tint than they did when in the rough. A good deal of the colour 
in some rough stones seems to be concentrated in the crystal corners from 
4 
