gem miningThe  third  method  of  gemming  in  river  beds  is less common and calls for more arduous  and prolonged operations. A low, temporary, brush-wood  dam is built across a stream  to increase  the flow of water at a  selected  spot. Long-handled  shovels up to twelve meters or more in length with mammoty  heads at the ends  are  employed  by  six  to  eight  men  to  drag  the river  bed at  a point  upstream  of the temporary  dam. The men standing in a row across the stream scoop out a hollow by removing the sand and exposing the illam layer in the river bed. The overburden of sand and silt is carried away by the agitated water and the coarse material  and the gravel comprising the illam is raked up and collected in a low ridge. This partly sorted illam is next removed in baskets to the bank of the stream and the gravel washed in the usual way. This method of gemming can only be employed when the gravel occurs at shallow depths.

The methods of mining employed are simple, almost primitive, using only manual labour and with the exception of pumps no mechanical means are used. They involve little capital outlay and are time honored methods  which are quick and  reasonably  efficient and particularly suited to the nature and mode of occurrence of the gemstone bearing gravels. Besides, mining is seasonal and normally extends from December to May as most of the gemstone bearing lands are flooded or partly sub merged during the wet season. With sporadically distributed gravels, the use of mechanical means of excavation or dredging is not feasible. Some degree of mechanization has been introduced in recent years for the washing of the gravels.