Botswana intends to renegotiate its proposed purchase of a stake in Belgian gem dealer HB Antwerp to double the size of its shareholding at no extra cost following the downturn in the diamond market, the country’s mines minister said on Tuesday.

Botswana is the world’s biggest diamond producer by value, meaning its economy has been disproportionately hit by a drop in demand for diamonds caused by a global economic slowdown.

Finance ministry budget documents showed in February that the country had set aside 890 million pula ($65.95 million) for the 24% stake, valuing the Belgian company at about $275 million.