The company received highest price for a 135.4 carat diamond which was sold for $6.37m with an additional three diamonds selling for more than $2.5m each.

One regular tender, where 80,000 carats will be on sale including more than 30 single stones larger than 10.8 carats, will be held by the company during its third quarter.

Lucara Diamond president and CEO William Lamb said, "This sale demonstrates that the market remains very strong for large and exceptional diamonds adding significantly to the value of Karowe Mine which continues to outperform expectations."

The company has also appointed Dr. John Armstrong as vice president – mineral resources of the company, effective from 03 September 2013.

With over 25 years of combined experience in mineral exploration, mining and government, Dr. Armstrong in his new role will replace Dr. Ott, who will be retired but who will be retained on a consultancy basis.

Armstrong was involved in the planning and execution of diamond exploration and sampling programs ranging from generative to delineation and valuation.