The openpit heap leach operation will produce 200,000ozpa once fully ramped-up.
Nordgold said the US$250 million project was done on-time and on-budget.
The company delisted from the London Stock Exchange in 2017 and is 99%-owned by billionaire Severstal chairman Alexey Mordashov.
Nordgold CEO Nikolai Zelenski said Gross would inspire further development.
"Gross is a significant new asset for Nordgold and turns us into a one million ounce producer for the first time in our history," he said.
"This gives us even greater confidence as we look to develop our Montagne d'Or asset in French Guiana which is expected to be a major catalyst for much needed economic growth in the country."
Nordgold produced 448,000oz in the first half of 2018 at an all-in sustaining cost of $1,009 per ounce, handing Mordashov a profit of $68.8 million.
