A Perth company believes it's close to a mother lode of large diamonds in Africa

Some of the diamonds found in Angola

An Australian mining company believes it’s close to finding the mother lode, the source of a series of large gems discovered in Angola, including a record 400-carat stone.

The Perth-based Lucapa Diamond Company found the biggest diamond unearthed in Angola, at 404.2 carat, or about 80 grams.

The news sent the company’s share price up by one third before closing at $0.41, 28% higher.

The diamond is the fourth 100+ carat diamond recovered from alluvial digging at the Lulo diamond project in Lunda Norte province.

“We will put it up to our normal buyers and sell it in its rough (uncut) form,” CEO Stephen Wetherall told Business Insider.

“When you have a new production coming online, people will buy it and first cut it and polish it to see the type of material it is and how the colours come out.

“These are buyers who have been taking our product for the last six months and like what they saw. They are champing at the bit and we are going to give them that opportunity to buy it.”

The record 404.2 carat Lulo diamond

The diamond is the 27th biggest recorded in the world and the biggest discovered by an Australian company. The previous record for Angola’s largest diamond belonged to the Angolan Star, a 217.4 carat gem recovered in 2007.

Wetherall hasn’t given as estimate but, based on recent average prices, the big diamond is worth more than $800,000 just on its weight alone. Cut and mounted into a piece of jewellery, the price could easily run into many millions.

“It’s a special stone, it’s Angloa’s largest stone, of national interest and iconic,” Wetherall says.

“But at the end of the day it’s all about what comes out of it when polished. The guy who buys it will see what comes out and will make an offer.”

Wetherall says he believes his company is getting close to the source, the Kimberlite rock where diamonds are formed.

“The theory is that large stones don’t travel far and our previous largest was 133 carats and now we have a 400 carats,” he says. “Our interests in this area was already high but now it’s even higher. We’ve got work to do to look for the source.”

In the meantime, Lucapa’s local partners Endiama and Rosas & Pétalas will be choosing a proper name for the diamond. The previous record for Angola’s largest diamond was called the Angolan Star, the 217.4 carat gem.

Over the 12 months since the company started operations at Lulo, 10,372 carats have been recovered, not including the latest find. In the December quarter, the company recorded diamond revenues of $8.1 million at record quarterly average selling prices of $2141 per carat.

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