Earnings before interest, taxes, depreciation and amortization (EBITDA) was $60.8m for the quarter, compared to $69.6m for the same period last year.
The Ekati diamond mine generated gross margins and EBITDA margin as a percentage of sales of 9.7% and 32% respectively in Q1.
The Diavik segment generated gross margins and EBITDA margins as a percentage of sales of 17.6% and 44% respectively.
Dominion Diamond acting chief executive officer Brendan Bell said: "Despite a slightly weaker market to start the year, our first quarter sales remained robust.
"However margins reflect the fact that as forecast, fiscal 2016 is a transitional year for the Ekati Diamond Mine, with a lower value ore mix processed until the rich Misery main pipe comes on-stream in early calendar 2016."
Dominion Diamond has ownership interests in Ekati and Diavik mines that are located in the low political risk environment of the Northwest Territories in Canada.
The company operates and owns a 88.9% interest in Ekati diamond mine and holds a 40% stake in the Diavik diamond mine.
