Lucara Diamond has recovered a series high quality Type IIa, 336 carat diamond from its Karowe mine in Botswana.
The three other exceptional diamonds recovered include a 184 carat stone, a 94 carat and an 86 carat stone. A 12 carat pale pink diamond was also identified, and its color will be confirmed after cleaning.
In 2013, Lucara announced recovery of the first large diamond from the Karowe and has since recovered 216 diamonds that have sold for more than $250,000 each.
Twelve of the recovered diamonds so far have been sold for more than $5m each.
Lucara president and CEO William Lamb said: "The ongoing recovery of large exceptional diamonds from the Karowe mine continues to support the resource estimates.
"This resource has consistently produced significant value for the Company and its shareholders and the ongoing recovery of high value stones sets Lucara apart from most other diamond producers."
For the second quarter of this year, Lucara reported revenues of $38.1m, compared to $71m for the same period in 2014.
Lucara Diamond’s assets include the Karowe mine in Botswana, two stone exploration licenses in Botswana and the Mothae project in Lesotho.