Stornoway Diamond’s Renard Quebec mine might prove almost twice as profitable to develop following a revised preliminary assessment, making it one of the best undeveloped diamond sites in the world.

The company said that an updated economic assessment of the mine, in the James Bay region, indicates that total diamond production at Renard will be 30 million carats with a conceptual mine life of 25 years.

The Renard project may generate a pre-tax internal rate of return of 25%, up from a 2008 forecast of about 14%.

Stornoway board chairperson Eira Thomas said the study has established Renard as one of the best undeveloped diamond deposits in the world, well on track to becoming Quebec’s first diamond mine.

The company expects to complete its full feasibility study of an underground and open-pit mine at the end of 2011.

Renard is located near the Otish Mountains on Stornoway’s Foxtrot property and is a joint venture with Quebec Government mining development agency SOQUEM.