Its proceeds were US$26.4 million, for 451,000 carats sold at a value of US$59/ct - less than half the $142/ct received in the March sale, which the company said was expected as certain fancies and specials had been moved up to the earlier sale.
Mountain Province interim president and CEO David Whittle said the company was very pleased with the April results.
"Exceeding our expectations, they indicate a positive year-on-year firming trend within diamond markets generally," he said.
The company last week completed its friendly acquisition of explorer Kennady Diamonds, which neighboured Mountain Province's 49%-owned Gahcho Kué mine in Canada's Northwest Territories, operated by De Beers (51%).
Commercial production was declared at Gahcho Kué in March 2017 and revenue and costs from four of last year's 10 diamond tender sales last year were recorded against construction costs, with Mountain Province reporting an average realised sale price of US$70/ct for the year.
The company expects to release its first quarter production results next week.