(IDEX Online) - Rough diamond sales at Debswana fell by 17 per cent during the first half of this year, amid ongoing weak demand.The 50/50 joint venture between De Beers and the Botswana government sold 12.7m carats for $2.179bn, down from $2.622bn during the same period last year, according to the Bank of Botswana.It follows a bumper year for Debswana in 2022, when rough sales increased by almost a quarter as buyers shunned Russian goods.Total revenue for the year hit a record $4.588bn, but market uncertainties have hit sales of late.Debswana mines the vast majority of Botswana's diamonds. At the moment De Beers sells 75 per cent and state-owned Okavango Diamond markets the remainder.A new deal agreed last month will see Okavango's share increase to 50 per cent over the next decade.Pic shows Orapa mine, courtesy Debswana.