BRAZILIAN DIAMONDS
gullies
and fissures in the rocks, river bottoms which have been covered by
debris from washings on the streams above, and the like; but with
deposits of uncertain richness, which may be here or may be there over
square miles of very rough country, the odds seem to be largely against
adequate returns for an expensive equipment.
The
general character of the Brazilian diamond field indicates a wide
upheaval of the basic granite rock leaving a very rough and broken
surface full of huge gullies and fissures. In these fissures, and in
the basins or depressions in the granite, are deposits of disintegrated
material forming substances and conglomerates of varying hardness in
which diamonds occur. The indications are that during a period of
disruption the material was exuded from the interior of the earth.
What
is commonly called the first water in diamonds means the greatest
purity and perfection and must be a drop of the clearest rock water.
When one speaks of a diamond falling short, more or less of that
perfection, it is expressed by saying it is of the second or third
water, etc., until a stone may properly be called a colored one.
Authorities
conflict regarding the output of the Brazilian mines in the early
years after their discovery. Up to 1740 estimates of the yearly
production varied from 20,000 to 144,000 carats. From 1740 to 1772 the
official reports gave an average production of about 52,000 carats per
year. In round figures, the production from 1740 to 1772, 1,700,000
carats; and from 1772 to 1818, 1,300,000 carats. In all up to 1818,
3,240,000 carats; and up to 1850
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