The De Beers concern treats 8;000 carloads -- about 6,000 tons--of blue rock per day, and the result is three pounds of diamonds.

Value, uncut, $50,000 to $70,000.

After cutting, they will weigh considerably less than a pound, but will be worth four or five times as much as they were before.
All the plain around that region is spread over, a foot deep, with blue rock, placed there by the Company, and looks like a plowed field.
Exposure for a length of time make the rock easier to work than it is when it comes out of the mine.

If mining should cease now, the supply of rock spread over those fields would furnish the usual 8,000 car-loads per day to the separating works during three years.

The fields are fenced and watched; and at night they are under the constant inspection of lofty electric searchlight.