Firm has determined it's not economically viable to extend the life of the diamond mine, which can only be accessed by air year round, or by a winter road for five or six weeks in January and February.
Petra Diamonds Ltd's first quarter revenue fell by 17 percent after Tanzanian government last month seized consignment of diamonds from its Williamson mine.
Over 50% of the proceeds will be used to fund clean water, electricity, school, medical facilities, bridges and roads, none of which are currently available in the village of Koryardu, where the diamond was found.