An ASX-listed mining company has unearthed a rare pink diamond that is believed to be the largest found in 300 years.

Discovered at the Lulo alluvial diamond mine in Angola, the 170 carat pink diamond – dubbed the Lulo Rose – is among the largest pink diamonds ever found, the WA-based Lucapa Diamond Company told investors.

“Only one in 10,000 diamonds is coloured pink. So you’re certainly looking at a very rare article when you find a very large pink diamond,” Lucapa CEO Stephen Wetherall said.

Pink diamonds get their colour from intense heat and pressure during the stone’s formation in the earth, which distorts the crystal lattice and results in the pink hue.

Mr Wetherall hailed the “historic recovery”, saying the diamond was one of the rarest and purest forms of natural stones and would be sold at international tender.

Although the Lulo Rose would have to be cut and polished to realise its true value, in a process that can see a stone lose 50% of its weight, similar pink diamonds have sold for record prices.

The Pink Star, for example, was uncovered in Africa in 1999 and, over a two-year period, the original 132.5 carat rough diamond was transformed into a 59.6 carat vivid pink diamond.

It was then sold at a Hong Kong auction in 2017 for US$71.2 million (about $101.4 million) – the single most expensive diamond or jewel sold at auction, to date.

“A vivid pink diamond this size is a total freak of nature,” Gemological Institute of American executive vice president Tom Moses said at the time.

“There are very few important pink diamonds over 20 carats. It is less likely that we will see more important sizable pinks. As the mines age, the deeper the hole, historically the yield seems to be lower and lower.”

This makes the discovery of the Lulo Rose – which at 170 carats outmuscles the Pink Star’s original 132.5 carats – all that more impressive. And with both diamonds classed as type IIa (flawless), the stone has the credentials to equal or even surpass the Pink Star’s pay day.

Having recovered the Lulo Rose from a river bed, Lucapa has now begun its search for the site’s underground deposits, which will be the main source of the diamonds, Mr Wetherall said.

“We’re looking for the kimberlite pipes that brought these diamonds to the surface,” he said.

“When you find these high-value large diamonds … it certainly elevates the excitement from our perspective in our hunt for the primary source.”

Sources:

• Lucapa Diamond Company, ASX Announcement
• naturaldiamonds.com, Diamond Hall of Fame: The CTF Pink Star Diamond
• APN News, Big pink diamond discovered in Angola, largest in 300 years