Rough stone sorting or aggregation operations have been based in London for nearly 80 years.
De Beers chief executive officer Philippe Mellier told reporters here it was the first step in a process that should be complete by the end of 2013.
Mellier said the move would transform Botswana into a leading international centre, with about $6 billion worth of diamonds expected to flow through the country.
He added that the diamond market remained challenging in the short term, but was nonetheless an exciting time for Botswana to build on its rightful position as a leading diamond producing country.
Botswana and De Beers in September 2011 signed a 10-year deal to move its rough stone sorting and trading division from London to Gaborone.
Since it started mining diamonds in the early 1970s, Debswana — a company equally owned by Botswana’s government and De Beers — has been selling its diamonds exclusively to De Beers, who in turn shipped the diamonds to London for sale to customers.
Under the deal, Botswana will for the first time directly sell 10 percent of gem stones manufactured locally while De Beers will also increase the value of diamonds it makes available to manufacturing companies in the country to $800 million a year from the current $550 million.
Minerals minister, Ponatshego Kedikilwe said at the time it has long been the aim of the government to have diamonds from Botswana processed, sorted, marketed and sold in Botswana.
De Beers is a global leader in the exploration, mining and marketing of diamonds.
Cecil Rhodes, the colonial-era politician and mining tycoon, founded De Beers in 1888. His fortune financed his imperial adventures for Britain, founding the state of Rhodesia which later became modern Zambia and Zimbabwe.