Page:Popular Science Monthly Volume 41.djvu/475

Rh moisture soon have a wonderful effect upon it. Large pieces which were as hard as ordinary sandstone when taken from the mine, soon commence to crumble. At this stage of the work, the winning of the diamonds assumes more the nature of farming than of mining; the ground is continually harrowed to assist pulverization by exposing the larger pieces to the action of the sun and rain. The blue ground from Kimberley mine becomes quite well pulverized in three months, while that from De Beers requires double that time. The longer the ground remains exposed, the better it is for washing." The process of exposure being completed, the blue ground is then carried to very large, elaborate, and costly washing machines, in which, by means of the action of running water, the diamonds are separated from the ordinary earth. It may be mentioned that in this process one hundred loads of blue ground are concentrated into one load of diamondiferous stuff. Another machine, the "pulsator," then separates this latter stuff, which appears to be a mass of blue and dark pebbles of all shapes, into four different sizes, which then pass on to the assorters. "The assorting is done on tables, first while wet by white men, and then dry by natives." The assorters work with a kind of trowel, and their accuracy in detecting and separating the diamond from the eight different kinds of mineral formations which reach them is almost unerring. "The diamond occurs in all shades of color from deep yellow to a blue white, from deep brown to light brown, and in a great variety of colors, green, blue, pink, brown, yellow, orange, pure white, and opaque." The most valuable are the pure white and the deep orange. "The stones vary in size from that of a pin's head upward; the largest diamond yet found weighed 428½ carats. It was cut and exhibited at the Paris Exhibition, and after cutting weighed 228½ carats.

"After assorting, the diamonds are sent daily to the general office under an armed escort and delivered to the valuators in charge of the diamond department. The first operation is to clean the diamonds of any extraneous matter by boiling them in a mixture of nitric and sulphuric acids. When cleaned they are carefully assorted again in respect of size, color, and purity." The room in the De Beers office where they are then displayed offers a most striking sight. It is lighted by large windows, underneath which runs a broad counter covered with white sheets of paper, on which are laid out innumerable glistening heaps of precious stones of indescribable variety. In this room are concentrated some 60,000 carats, the daily production of the Consolidated Mine being about 5,500 carats. "When the diamonds have been valued they are sold in parcels to local buyers, who represent the leading