Value of huge Botswana diamond 'unknown'

Lucara mining firm attracts many inquiries to buy 1,111-carat gem but says stone not yet valued as it's too big for onsite equipment and must be flown to Antwerp

The Canadian mining company which this week unearthed the world's largest diamond in more than a century says it cannot put a value on the 222g (7.8oz) stone.

The 1,111-carat gem was hauled from an open pit mine in central Botswana, by the Lucara Diamond Corporation, a Vancouver based firm.