http://b4hntuy3fimfh2227vf4f74emnya7p35i5brtqujs6leqvtclfwvjbqd.onion/doc/physics/diamonds-crookes/The%20Project%20Gutenberg%20eBook%20of%20Diamonds,%20by%20William%20Crookes..html
They are
much rolled and etched, and contain a good
proportion of first-class stones; they are
of very good quality, as if only the better
and larger stones had survived the ordeal of [12] knocking about. Diamonds from the drift
fetch about 40 per cent more than those
from Kimberley; taking the yield of the
Kimberley and De Beers mines as worth
all round, large and small, 26s. 6d. a carat,
those from the drift are worth 40s.