JOHANNESBURG (AP) — A big pink diamond of 170 carats has been discovered in Angola and is claimed to be the largest such gemstone found in 300 years.

Called the “Lulo Rose,” the diamond was found at the Lulo alluvial diamond mine, the mine’s owner, the Lucapa Diamond Company, announced Wednesday on its website.

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

The pink gemstone is expected to fetch a high value when auctioned, but Wetherall said he doesn’t know what kind of premium will be paid because of its color.

Lulo is an alluvial mine which means the stones are recovered from a river bed. The Lucapa company is searching for the underground deposits, known as kimberlite pipes, which would be the main source of the diamonds, said Wetherall, speaking from the company’s headquarters in Australia.

“We’re looking for the kimberlite pipes that brought these diamonds to the surface,” Wetherall said. “When you find these high-value large diamonds … it certainly elevates the excitement from our perspective in our hunt for the primary source.”

About 400 staff are employed at the Lulo mine which has already produced the two largest diamonds ever found in Angola, including a 404-carat clear diamond, he said.

The pink gemstone is the fifth largest diamond found at the mine where 27 diamonds of 100 carats or more have been found, according to Lucapa.

The pink diamond will be sold by international tender by the Angolan state diamond marketing company, Sodiam. Angola’s mines make it one of the world’s top 10 producers of diamonds.

“This record and spectacular pink diamond recovered from Lulo continues to showcase Angola as an important player on the world stage for diamond mining and demonstrates the potential and rewards for commitment and investment in our growing diamond mining industry,” Diamantino Azevedo, Angola’s Minister of Mineral Resources, Petroleum and Gas said, according to the Lucapa website.

The pink diamond is an impressive size but many clear diamonds are larger than 1,000 carats. The Cullinan diamond found in South Africa in 1905 tips the scales at 3,106 carats and it’s in the British Sovereign’s Scepter.