This
was a slow and tedious process, at best. The percentage of precious
stones won from the gravel necessarily depended on the care,
expertness, and eyesight of the workers. Experience proved that fairly
expert gold placer miners were not equally competent in handling
diamond-bearing gravel, and slave labor was not diligent or
trustworthy. The loss was increased by the greedy pressure for big and
quick returns, and the premium set on the extraction of large stones.
When,
in the course of mining, streams were diverted from their beds by dams
and sluiceways, there was urgent need of hurrying, for the frail dams
could not bear the rush of a flood in the rainy season, and it was
necessary to remove the gravel from the stretches of river beds before
the heavy rains fell.
