Falling off of Yield with Depth
According to tables furnished by the De Beers Company, the yield of the De Beers and Kimberley mines has declined as the depth increases. At the same time the value of the stones has risen, and diamonds are more expensive to-day than at any previous time.
| NUMBER OF CARATS[5] | VALUE | ||
| YEAR | PER LOAD | PER CARAT | |
| s. | d. | ||
| 1889 | 1·283 | 19 | 8·75 |
| 1890 | 1·15 | 32 | 6·75 |
| 1891 | 0·99 | 29 | 6 |
| 1892 | 0·92 | 25 | 6 |
| 1893 | 1·05 | 29 | 0·6 |
| 1894 | 0·89 | 24 | 5·2 |
| 1895 | 0·85 | 25 | 6 |
| 1896 | 0·91 | 26 | 9·4 |
| 1897 | 0·92 | 26 | 10·6 |
| 1898 | 0·80 | 26 | 6·2 |
| 1899 | 0·71 | 29 | 7·2 |
| 1900 | 0·67 | 35 | 10·2 |
| 1901 | 0·76 | 39 | 7 |
| 1902 | 0·76 | 46 | 5·7 |
| 1903 | 0·61 | 48 | 6·3 |
| 1904 | 0·54 | 48 | 11·8 |