The total proven and probable reserves were recorded at 2.9 carats per tonne, for 53.5 million carats for the mine at Lac de Gras, Northwest Territories.

The company noted that the new significant data was concluded from processing the samples from the 2011 deep drilling program on the A-154 North and A-418 kimberlite pipes.

An additional new reserve of 500,000 million tonnes was added from the updated A-154 North model, while it also confirmed 1.3 million tonnes of probable reserve; the company also noted a new resource of 400,000 million tonnes at depth.

No significant updates were provided for A-154 South and A-21 kimberlite pipes, since they were not a part of the drilling program.

Harry Winston noted in a statement, "The A-21 pipe remains a resource while economic studies continue, but would be promoted to a reserve once a feasibility plan is approved."

In addition, total measured resources at the end of 31 December 2012 were reported to be 3.6 million tonnes at 2.8 carats per tonne, for 10 million carats.

Also, an indicated resource of 0.4 million tonnes at 2.6 carats per tonne, with 1 million carats were reported at Diavik diamond mine.