Kimherley Diamonds : Especially Cleavage Diamonds. 
77 
Table Showing the Percentages of each Class of Diamonds from the 
Bultfontein Mine. 
Year, 
Carats sorted. 
Stones. 
Cleavages. 
Eubbisli and ])ort. 
M. 
Per cent. 
Per cent. 
Per cent. 
1902-4 
265 
29-54 
29-03 
41-43 
1905 
291 
30-84 
34-87 
34-29 
1906 
533 
28-87 
36-27 
34-85 
1907 
506 
26-6r 
35-73 
37-66 
1908 
398 
26-56 
33-48 
39-96 
1909 
670 
25-05 
32-01 
42-94 
1910 
678 
23-89 
34-08 
42-04 
1911 
778 
23-87 
35-70 
40-43 
1912 
855 
23-12 
36-63 
40-25 
1913 
787 
22-25 
36-30 
41-45 
1914-16 
992 
23-19 
32-64 
4416 
The first line is not perhaps fairly comparable with the others, since it 
represents the first years in which systematic work was begun by the 
De Beers Company, and no doubt some clearing up from previous irregular 
work by various small companies had to be done. But from 1905 onwards 
there seems to have been a pretty clear increase, on the whole, in the rubbish 
and bort of about 10 per cent. At the same time the cleavages have been 
very little affected, while the ratio of stones has decreased from sav 30 to 
23 per cent. If we assume that the increase of rubbish and bort is due to 
improved mining methods, and reduce the ratio of rubbish and bort accord- 
ingly, this would indicate that the quantity of stones found has not decreased 
much, if at all, and may indeed have increased somewhat. 
With this there does seem to have been an increase in the actual yield 
of brown diamonds as compared with the rest. The following are the 
separate percentages of brown and other cleavages : 
Year. 
Brown cleavages. 
Other cleavages 
Per cent. 
Per cent. 
1902-4 
3-92 
25-11 
1905 
2-96 
31-9] 
1906 
3-45 
32-80 
1907 
3-85 
31-88 
1908 
3-91 
29-57 
1909 
3-52 
28-49 
1910 
3-84 
30-22 
1911 
3-88 
31-82 
1912 
4-15 
32-48 
1913 
4-28 
32-02 
1914-16 
4-38 
28-26 
