Botswana's state-run Okavango Diamond Company unveiled on Wednesday what is believed to be the largest blue diamond ever discovered in the southern African country, which is one of the world’s top producers.

The 20.46-carat, oval-shape fancy precious rock has been named "The Okavango Blue" in honour of the Okavango Delta, the country's wildlife-rich world heritage site.

From all coloured diamonds, blue stones are the most unusual and so the miner says its find is one of the rarest in the world.

"It is incredibly unusual for a stone of this colour and nature to have come from Botswana – a once-in-lifetime find, which is about as rare as a star in the Milky Way," Okavango Diamond Company managing director Marcus ter Haar said in a statement.

"It sits in the very top bracket of all-time historical blue diamond finds

especially because

only a very small percentage of the world's diamonds are classified as fancy colour," he noted, adding the company expects to sell the stone by the end of the year.

 Source: mining.com