http://b4hntuy3fimfh2227vf4f74emnya7p35i5brtqujs6leqvtclfwvjbqd.onion/doc/physics/diamonds-crookes/The%20Project%20Gutenberg%20eBook%20of%20Diamonds,%20by%20William%20Crookes..html
The gravel is dug and put
into a machine resembling the gold miner’s
dolly, where it is rocked and stirred by rakes,
with a current of water flowing over it.
Here all the fine stuff is washed away and
a rough kind of concentration effected.
The residual gravel is put on a table and
sorted for diamonds—an operation performed
by the master.