DISCOVERY 



269 



The stream-washing is much more simple and 

 methodical. The stream-bed consists wholly of well 

 water-worn granite, and of boulders and pebbles of 

 gneiss and garnetiferous granite ; below the surface- 

 layer the boulders and pebbles are embedded in 

 latterite, much decomposed and with a considerable 

 quantity of kaoline ; it is in this that the gems are 

 found. The process of recovery is by washing in a 

 conical-shaped basket made of cane, about 2 ft. in 

 diameter at the top and 12 in. deep to the apex of 

 the cone. A curious feature of these baskets is that 

 they are water-tight. They hold about 30 lb. of wash- 

 gravel : the gravel is placed in the basket, which is 

 then filled with water by submersion ; a rotary and at 

 the same time a tilting motion is applied, which causes 

 the lighter particles to come to the surface and pass 

 out over the basket edge. This process is repeated 

 until only a small quantity of the wash-gravel con- 

 centrates are left in the cone of the basket. This is 

 then dumped on to a mat and hand-picked for any gems 

 it may contain. All natives in the gem-districts are 

 expert gemmers in their own crude way. The men and 

 boys generally do the digging ; the women are certainly 

 the best washers I have ever seen ; in fact, they can 

 get a perfect concentrate either by washing with water 

 or by dry-vanning. 



In dry-vanning they use a basket made like a 

 housemaid's dusting-pan, and by dexterously throwing 

 up the gravel repeatedly in the air and with a jerk, 

 they pass all material of light specific gravity on to the 

 ground and collect the heavy concentrates at the base 

 of the basket. Impressed with the expertness of the 

 vanning, I made a test of gems from three separate 

 minerals, thorianite, and ordinary gravel. The vanner 

 never lost a single gem or thorianite crystal, and then, 

 to show how expert she was at her job, separated 

 the gems from the thorianite. Fig. 2 shows this 

 woman at work on this actual vanning test. 



I have just said that the method of washing gem- 

 deposits is crude. This only applies to the working of 

 the wash-gravel, not in the recovery of the concentrates. 

 The crude methods of working the deposits seem due 

 to the natural laziness of Eastern races. They like 

 better to squat or sit down and scoop up small quantities 

 with a coconut shell than to stand up and use a shovel. 

 Time is no object to them, and gemming is only a pas- 

 time to keep them occupied when they have nothing 

 else to do after the rice harvest is in, and it may bring 

 in a few rupees should they be lucky. 



The Order of Merit in the Stones 



The classification of precious and semi-precious 

 stones varies considerably in the minds of mineralogists 



or jewellers. The mineralogist classifies according to 

 the chemical composition, crystallisation, hardness, 

 and specific gravity. The jeweller, disregarding these 

 essentials, jumbles them up and classifies them mostly 

 by colour, disregarding the fact that the composition 

 is of the highest importance for value. As the principal 

 demand of gems is for ornamental purposes, it matters 

 very little whether the gem is hard or not, or whether 

 it is in the first or second classification. Effect is the 

 purchaser's object, with the satisfaction of knowing it 

 is not wholly common glass. There is a considerable 

 amount of fraud in the ornamental-stone j^business. 



^5&^^^^^SzSfe^ 



FlO. 2.— A WOMAN SEPARATING GEMS. 



since present-day chemists can now construct, from the 

 analysis of real gems, glass substitutes that only an 

 expert can detect. Even sapphires and rubies can 

 be made with all the essentials of the natural stone, 

 i.e. of corundum-construction. In the case of very 

 small stones these reconstructed stones no doubt will 

 pass as genuine, but in the larger specimens there is 

 always to be seen a very minute bubble or air-space 

 which proves their origin. The following classifi- 

 cation by Kluge may be of interest ; I quote it 

 from Precious Stones, by Dr. Max Bauer and L. J. 

 Spencer, M.A. : 



