Mining giant Rio Tinto said on Wednesday it has unearthed a ‘remarkable’ 12.76 carat pink diamond in Australia, the largest of the rare and precious stones ever found in the resources-rich nation.

Named the Argyle Pink Jubilee, the huge rough stone was found at Rio's pink diamond operations in the Kimberley region of Western Australia and would take 10 days to cut and polish, the miner said.

"This rare diamond is generating incredible excitement," said Josephine Johnson from Rio's Argyle Pink Diamonds division.

"A diamond of this calibre is unprecedented - it has taken 26 years of Argyle production to unearth this stone and we may never see one like this again.

"The individual who gets to wear this remarkable pink diamond will be incredibly lucky indeed."

Though it would not speculate on how much the Jubilee was worth, Rio said extremely high quality pink diamonds could fetch in excess of US$1 million per carat, meaning it is likely to go for at least $10 million.

The light pink Argyle Jubilee is a similar colour to the 24-carat Williamson Pink given to Britain's Queen Elizabeth II as a wedding gift, which was later set into a Cartier brooch for her coronation.

The Williamson was discovered in Tanzania in 1947 and is ranked among the finest pink diamonds in existence. It is the ninth-largest in the world.

A Rio spokesman has said the recent discovery was named in honour of the long-reigning British monarch, who is celebrating 60 years since her accession to the throne - her diamond jubilee.

"This is the Queen's diamond jubilee year and there is a parallel in that the Queen had a solitaire pink diamond, gifted to her - The Williamson Pink - and set in the centre of a flower brooch in the year of her coronation," he said.

When asked if Rio was targeting the Argyle Jubilee diamond at the Queen the spokesman said: "Only if she is shopping for new jewellery. She will have lots of competition."

Rio produces more than 90 per cent of the world's pink diamonds from the Argyle mine, and said large stones like the Jubilee typically went to museums, were gifted to royalty or end up at prestigious auction houses like Christie's.

Christie's had only auctioned 18 polished pink diamonds larger than 10 carats in its 244-year history, Rio added.

Soaring demand for the extremely rare jewel has seen pink diamond prices skyrocket in the past 20 years and they are now among "the most concentrated forms of wealth on earth and well in excess of white diamonds," Rio said.

The miner describes it as an ‘elite and discrete’ market with buyers including royalty, heads of state, celebrities and ‘other very wealthy individuals.’

When the Jubilee diamond has been cut and polished it will be graded by international experts and showcased globally in private settings before being sold by invitation-only tender later this year.

It is not known how the diamonds acquire their pink tinge but it is thought to come from a molecular structure distortion as the jewel forms in the earth's crust or ascends to the surface.

According to local Aboriginal folklore, the Argyle mine was formed when a barramundi fish jumped through the net of three local hunters. The diamonds are its scales glinting in the sun and the pink ones are the fish's heart.