A team of miners working for an Australian company has dug up what could be the largest piece of diamond ever to be found in Angola. The massive 404-carat gemstone is believed to be worth about $14 million.

Miles Kennedy, chairman of the Perth-based Lucapa Diamond Company, said that they were not used to determining the value of a 400-carat diamond.

Miners from the company found the large diamond in one of its mines located some 300 miles east of Luanda, Angola's capital city.

Kennedy pointed out that when they first surveyed the 3,000-square kilometer (1,158-square mile) property, they thought that it was at a very remote area, being located 700 kilometers (435 miles) inland from the Angolan coast.

He said that discovering the massive diamond on this site is a form of vindication for all the years of hard work they have done.

According to Lucapa, the gemstone is the largest of its kind to be found in Angola. It is also the biggest one to be unearthed by a miner from Australia.

The company said that the diamond measures about seven centimeters (2.75 inches).

Angola is considered the fourth largest diamond-producing country based on value.

Kennedy has been in search of diamonds ever since he established the Ellendale mine in the Kimberley region of Western Australia during the 1990s.

When he went on to start The Lucapa Diamond Company, Kennedy brought his geology team from Ellendale to his mine in Angola.

"I started the Ellendale diamond mine and was there from 1993 to 2007, so 14 years, and in that time we only got one diamond greater than 10.8 carats, known as a special diamond," Kennedy said.

Through Lucapa, Kennedy has now discovered more than 100 special diamonds over the past six months alone.

He said that he plans to use the sizeable cash injection from the sale of the diamond to expand Lucapa's operations to include other areas.

The discovery of the 404-carat diamond comes months later after another firm, Lucara Diamond, unearthed a massive 1,111-carat diamond of its own in Botswana.

The Lucara find is considered to be the second-largest diamond in the world, following only the 3,106-carat Cullinan diamond discovered in a mine in South Africa back in 1905.