Inside the Democratic Republic of Congo's Diamond Mines | TimeAug 26, 2015 . In the Democratic Republic of Congo, almost all diamond mining is done by hand. It's a labor-intensive process that requires hauling away layers of dirt and rock, sometimes 50 feet deep, to expose ancient beds of gravel where the crystals are found. Miners then wash and sift that gravel one shovelful at a.diamonds from congo mining process,Congo, Democratic Republic - Mining and Minerals | exportJul 20, 2017 . The DRC is the largest producer of cobalt globally, accounting for 51 percent of global production in 2015 according to the US Geological Survey (USGS) Mineral Commodity Summaries 2016 report. It was the second largest producer of industrial diamonds in 2015, contributing about 24 percent of global.