The decline was due to the COVID-19 pandemic that saw global travel restrictions being put in place to curb the spread of the virus.
Botswana's borders were closed in March, which made it difficult for foreign diamond buyers to travel to the southern African country for monthly diamond sales conducted by De Beers in Gaborone.
Debswana, a joint venture between Botswana and De Beers, shipped rough diamonds worth $287-million in the third quarter of 2020compared to $863-million, a year earlier.
Botswana gets about 30% of its government revenues from diamonds, which account for 70% of exports.
Botswana's economy is this year expected to record an 8.9% contraction due to the COVID-19 pandemic.
Mathew Nyaungwa, Editor in Chief of the African Bureau, Rough&Polished