Kimberley Diamonds : Esjjecially Cleavage Diamonds. 
79 
Here we find, so far as the statistics can show it, a decrease in the per- 
centage of stones of about 7 per cent, (about the same as that of Bultfontein 
in a little shorter time); an increase of cleavage of about the same amount; 
and a remarkable fluctuation in the percentages of rejection chips, rubbish, 
and bort, the curve of these showing, on the whole, a maximum in 1904, 
followed bj a minimum in 1910, and after that a rise to the present time. 
Curiously enough, the brown stones show a uniform decrease with time, 
whereas the brown cleavages show a definite increase, thus : 
Year. Brown stones. Brown cleavages. 
Per cent. Per cent. 
1898 . 2-82 . 5-17 
1899 . 3 10 . 6-35 
1900 . 2-97 . 6.44 
1901 . 3-55 . 6-20 
1902 . 3-33 . 7-15 
1903 . 3 14 . 7-22 
1904 . 2-62 . 8-19 
1905 . 2-49 7-63 
1906 . 2-37 . 8-21 
1907 . 2-65 . 9-65 
1908 . 2-29 . 9-61 
1909 . 2-28 . 10-70 
1910 . 217 . 10-84 
1911 . 1-97 . 9-64 
1912 . 1-89 . 1013 
1913 . 1-90 . 10-57 
1914-16 . 212 . 1013 
This is an extraordinary result, and requires more material for its full 
elucidation than has yet been accumulated. It would appear from the face 
value of the relative numbers that brown stones have shown a greater dis- 
position to break up in the deeper levels of the Wesselton Mine than in the 
upper ones. Also that brown diamonds (stones and cleavages together) 
have increased by about 3 per cent, in eighteen years, the fluctuations show- 
ing some, if small, agreement with those of rejection chips, rubbish, and 
bort. 
Comparing stones other than brown with cleavages other than brown, 
we have — 
Year. Stones not brown. Cleavages not brown. 
Per cent. Per cent. 
1898 . 28-89 . 11-89 
1899 . 26-43 . 9 12 
1900 25-17 . 9-07 
