De Beers, the world’s biggest rough diamond producer by value, was reduced to a shadow of itself during the second quarter as sales dipped to almost nothing and production plunged.

De Beers, which is 85% owned by Anglo American, one of the world’s major diversified resources companies, took a double beating from its major mining operations in Southern Africa, disrupted by the governments’ attempts to curb the spread of Covid-19 and a dearth of diamond buying caused by travel restrictions...