Gertler, whose grandfather co-founded Israel’s diamond exchange in 1947, arrived in Congo in 1997 seeking rough diamonds. The 23-year-old trader struck a deep friendship with Joseph Kabila, who then headed the Congolese army and today is the nation’s president. Since those early days, Gertler has invested in iron ore, gold, cobalt and copper as well as agriculture, oil and banking. In the process, he’s built up a net worth of at least $2.5 billion, according to the Bloomberg Billionaires Index.