The miner also extracted a 14.6-carat brown diamond and a number of smaller white diamonds, it reported.
The discoveries follow Merlin finding the “first” blue diamond at the mine in December, although the stone only weighed 0.124 carats.
Merlin Diamonds, formerly North Australian Diamonds, acquired the mine from Rio Tinto in 2004. It is the source of Australia’s largest diamond, a 104.73-carat stone.