Alfred Beit (1853-1906) has been called a financial genius. When he went to South Africa in 1875, no one could imagine that the son of converted Hamburg Jews would soon become one of the richest men of his time - thanks to the diamonds of Kimberley and the gold of the Witwatersrand.As a co-founder of De Beers Ltd. and close friend of Cecil Rhodes, the charismatic promoter of British imperialism…