for
computing the values of " wrought," or as we would say " cut,"
diamonds. First, the weight of the cut stone should be doubled, to
offset the loss of one-half in working; then this figure or figures
should be squared, and the product multiplied by the price per carat.
Thus a cut stone weighing one carat would be valued by multiplying 2 by
a by 2, or at £8, and a stone weighing 5 carats by multiplying 10 by 10 by 2, or at £200. By the second method, the calculation is made on the basis of the valuation of a cut stone weighing one carat, at £$, as
before determined. Then to find the value of a stone of any given
number of carats, multiply the number by 8, and the multiplicand will
be the estimated value of every carat in the stone. The total value may
then be reached by multiplying the number of carats by this
multiplicand. For example, if a given stone weighs 5|- carats, the
value of every carat in the stone will be found by multiplying by 8 to
be £4.1. Then multiply ^41 by 5-| and the result will be £210 is. 6d.;
the estimated value of a cut stone weighing 5^ carats. It was the
expectation of Mr. Jeffries that the general adoption of his method of
valuation would go far to fix the price of diamonds, and it did prevail
for more than a century before falling into disuse.
Production of Diamonds1
De Beers Consolidated Mines. During
the sixteen years ending June 30, 1904, the yield of De Beers
Consolidated Mines has been 36,000,000 carats of diamonds in round
figures, which would measure about 106 cubic feet, showing an average
of something more than 2,250,000 carats annually. Compared with this
product, the production of the other diamond fields of the world, with
the exception of Jagersfontein, is comparatively unimportant, not
exceeding 5 per cent of the total.
The Orange River Colony. The
principal diamond-producing mine in this colony is Jagersfontein, which
has averaged about 250,000 carats annually for several years past. The
Jagersfontein mine is controlled by the syndicate which has for many
years purchased the total production of De Beers Company.
1 See Appendix IX.
