There
are in India three extensive tracts, widely separated from one another,
in which the diamond has been sought for. The name of Golconda,
originally applied to a capital town (now a deserted fort in the
neighbourhood of Hyderabad), seems to have been used for a whole
kingdom; but the town itself is many miles distant from the nearest
diamond mines, and it was only the mart where the precious stones were
bought and sold. The second great tract occupies an immense area
between the Mahanuda and the Godavery rivers; and the third great tract
is situated in Bundelcund, near the capital of which —Punnah—some of
the mines are found. For those content with a slowly-paying occupation,
and a hard life involving close supervision of the workers, diamond
mining will pay, provided such persons possess capital sufficient to
last them a few years. The diamonds now are usually brought from
Parteal, close to the southern portion of the Nizam's dominions. The
deepest pits are not more than twelve feet. The matrix of the diamond
in those localities is a conglomerate sandstone. The appliances of
modern machinery for excavation, &c. directed by men of science,
may possibly bring to light gems that have not been discovered by the
rude native processes of search.
It
would be curious to ascertain the yield of diamonds in the East from
those mines in the last 350 years, and of Brazil in the last 150 years
since the discovery there, but no such data are obtainable, nor indeed
can any reliable estimate be formed of the value of the diamonds owned
in different countries. In the United States, diamonds to the value of
.£1,700,000 were imported in 1886. Two-million-and-a-half carats of
diamonds are cut yearly in Amsterdam. Precious stones being free of
duty in the chief European countries, no records are obtainable. The
Brazilian mines are said to yield about ^800,000 of diamonds, and
India, Borneo, and Australia ,£200,000, but these sums are
insignificant now in comparison with the South African yield of about
,£4,000,000 yearly.
The
only Indian mines now worked for diamonds are the northern ones in
Bundelcund; the produce, between ,£40,000 to £60,000, is sold locally,
and only about 100 carats are sent to Europe. Diamonds have been found
in .Sumatra and Celebes, but Borneo alone now produces a regular
supply, sending it is computed, about 3,000 carats annually into the
European market. The discovery of Cape diamonds has reduced the
Brazilian mining to a minimum of about 24,000 carats. And here it may
be desirable to explain what this fanciful diamond weight is. The
diamond grain is equal to about four-fifths of a troy grain, hence four
diamond grains are equal to one carat, or 3-174 troy
grains. But as half the rough stone has to be cut away in polishing, to
estimate the value of a rough diamond, we must ascertain its weight in
carats, double that weight, and multiply the square of this product by £2, which
may be taken as the average price of rough diamonds that are worth
cutting. Formerly, indeed, the price of diamonds was as to the square
of their weight, but this rule no longer holds good, as their value
mainly depends upon quality.
From
the four principal mines in Griqualand (which all lie within a circle
with a diameter of three miles), calculating the amount of
diamondiferous ground removed, and the known average yield per load in
each, it is found that not less than 33,000,000 carats of diamonds (or
more than 6-1/2 tons weight) must have been extracted since the first
discovery ; realising, in round numbers, £40,000,000 sterling.
The
yield of diamonds from the Kimberley mine alone, from the opening in
1871 to the end of 1885, is stated to have exceeded 17,500,000 carats,
equal to 3-1/2 tons weight of precious stones, in value about
£20,000,000.
To
obtain this, as many thousand tons of reef and ground have had to be
excavated. The mine is 450 feet deep, and the cubical contents of this
huge cavity measures about 9,000,000 cubic yards. Four thousand Kafirs
are employed at this mine, and more than 20,000 natives of Africa
arrive yearly at tile mines in search of work, so that the employment
of native labour, and the development of native trade, are incidental
benefits conferred on South Africa by the discovery of the diamond
fields.
