The syndicate in London to which Rhodes contracted to sell De Beers' entire production of diamonds in 1893 was made up of ten firms. These were Wernher, Beit & Company, Barnato Brothers, Mosenthal Sons & Company, A. Dunkelsbuhler, Joseph Brothers, I. Cohen & Company, Martin Lilienfeld & Company, F. F. Gervers, S. Neumann, and Feldheimer & Company. All these firms were interconnected by marriage and family ties, and all were owned by Jewish merchants. The fact that Jewish companies completely dominated the distribution of diamonds at the end of the nineteenth century was not particularly surprising. For a thousand years, diamonds had been almost entirely a Jewish business.
Until the early part of the eighteenth century, the entire world's supply of diamonds came from India. The caravans that brought them across Arabia traded these rare stones to Jewish traders in Aden and Cairo for gold and silver. The traders then resold them to Jewish merchants in Venice, Lithuania, and Frankfurt. It was a natural enterprise for the Jews scattered throughout central Europe: Since they were moneylenders, they had to concern themselves with assessing, repairing, and selling gems that had been offered to them as collateral for loans. They also had close connections with the Jewish trading centers in the Ottoman Empire through which all the Indian diamonds passed.