Blue Nile adopted a virtual model, in which it provides a shop window for suppliers yet does not put any of its own capital at risk.

ECONOMIST: Gentlemen prefer buying diamonds online

Online diamond retailer Blue Nile, then, is a twofer.

FORBES: Diamonds, Diamonds Everywhere

New customers, which are defined as individuals who have not made a prior purchase from Blue Nile, grew 7.8 percent in the fourth quarter of 2012 compared to the fourth quarter of 2011.

FORBES: Blue Nile Q4 Sales Up 21%

Jamam is one of three Upper Nile camps sheltering at least 113, 000 refugees who have crossed the frequently unmarked border to escape a counter-insurgency campaign in neighbouring Blue Nile state conducted by heavily armed Sudanese government troops.

ECONOMIST: A refugee crisis is miserably taking shape

Last weekend, the Government of Sudan signed a possible agreement of humanitarian access to Southern Kordofan and Blue Nile, where over 665, 000 people are in need.

WHITEHOUSE: Statement by the Press Secretary on World Humanitarian Day

From Khartoum, it is a bumpy drive into Ethiopia, where you can trace the Blue Nile to Lake Tana.

BBC: Journey down the world��s longest rivers