DIAMOND MINING 217
jadi
" and are worn as found. Diamond cutting is done at Pontianak,
Martapura and elsewhere. The art has been practiced in Borneo for
centuries. There are two shops in Martapura, one employing 2J0 and
the other about 150 workmen. Besides these about 300 polishers and 160
cleavers work independently. They are paid about fifty cents per carat
for cutting brilliants, and about thirty-five cents for cutting roses.
There are diamond-cutting establishments in Pagattam and Toenggoel also.
The
diamonds are found in the beds of the streams of to-day, and also in
the gravels of watercourses long since covered up. The miners sink
shafts through the overburden and tunnel into the diamondiferous
material in crude fashion, hoisting the gravel to the surface and
washing it in about the same way as all others do who work in alluvial
deposits. The Malays wash in a small bowl and show remarkable skill and
keen vision, picking out with unerring rapidity diamonds so small as to
escape entirely the observation of a European. The Malays mine and cut
in the crude Oriental ways of ancient times, but the Chinese adopt some
modern methods in their mining operations. The cutting is done by
natives.
The
deposits .of the Landak district are older than those of the
southeastern section around Martapura, but all the fields alike are
remarkable for the number of stones of deep color they afford. Borneo
has produced more diamonds, proportionately, of rare colors than any
other country; red, green, black and deep rich brown. According to Dr.
Theodor Posewitz, a mining engineer who resided in Borneo for some
years, as given by E. W. Streeter in his work on Precious Stones, the
natives have names by which they designate the most important.
