The operation of working for these precious jems is a very simple one. The
alluvial soil (the cascalhao) is dug up from the bed of the river, and
removed to a convenient spot on the banks for working. The process is as
follows:--a rancho is erected about a hundred feet long, and half that
distance in width; down the middle of the area is conveyed a canal,
covered with earth; on the other side of the area is a flooring of planks,
about sixteen feet in length, extending the whole length of the shed, and
to which an inclined direction is given; this flooring is divided into
troughs, into which is thrown a portion of the cascalhao; the water is
then let in, and the earth raked until the water becomes clear; the earthy
particles having been washed away, the gravel is raked up to the end of
the trough; the largest stones are thrown out, and afterwards the smaller
ones, the whole is then examined with great care for diamonds. When a
negro finds one, he claps his hands, stands in an erect posture, holding
the diamond between his fore-finger and thumb; it is received by one of
the overseers posted on lofty seats, at equal distances, along the line of
the work. On the conclusion of the work, the diamonds found during the day
are weighed, and registered by the overseer _en chef_. If a negro has the
good fortune to find a stone weighing upwards of seventeen carats, he is
immediately manumitted, and for smaller stones proportionate premiums are
given. There are, besides, several other works on this river, and on other
streams, but the supply of diamonds falls now considerably short of former
periods, and their produce scarcely defrays the expenses.

The Diamond District of the Serro do Frio is about twenty leagues in
length, and nine in breadth; the soil is barren, but intersected by
numerous streams. It was first discovered by some miners, shortly after
the establishment of the Villa do Principe. In working for gold in the
rivulets of Milho Verde and St. Goncalzes, they discovered some pebbles of
geometric form, and of a peculiar hue and lustre. For some years these