The unrivalled quality of Namibia's diamond assortment is the unique consequence of natural upgrading and concentrating processes. These processes were brought about by the sediment transfer from sources in the interior of southern Africa to deposition in "sinks" along the Namib Desert coast and in the Atlantic Ocean. Three major, long-standing transport pathways - which can be likened to conveyor belt systems - have been instrumental in moving diamondiferous sediment from source localities to sink areas:  Fluvial conveyor - principally the Orange-Vaal River drainage system Marine conveyor - in this passive margin setting, the Atlantic wave regime is vigorous with a strong north-bound longshore drift driven by a prevailing southerly wind regime Desert conveyor - the arid climate and prevailing southerly wind regime of the Namib Desert facilitates onshore movement of marine-derived sediment back into a land-based sink. En route, and over geological time, diamonds have been concentrated in a number of different placer types that span terrestrial and marine settings.