Lulo mine plant, where gravel is washed and screened for diamonds. (Image courtesy of Lucapa Diamond.)

Shares in Lucapa Diamond (ASX: LOM) jumped almost 5% on Monday after the Australian miner announced that resources at its Lulo mine in Angola rose 48% last year.

The company said the volume of diamonds with a viable chance of economic extraction at Lulo increased to 228,000 carats as of December 31, up from 153,870 carats the previous year. The newly identified resources, it said, could add an extra eight years to the deposit’s production.

Lucapa noted the updated figures are the result of an independent asset evaluation conducted by South Africa’s Z Star Mineral Resource Consultants.

The study assessed the resources at $1,897 per carat, a 5% decrease from $2,000 in December 2022, which partly reflects the decline of diamond prices last year. Diamond grades also decreased, but slightly — to 4.55 carats per 10 cubic meters.

Lucapa recovered 181,900 precious stones in 2023, a 45% increase from the previous year, with an average rough size of 1.26 carats per stone compared to 1.23 carats in 2022.

This increase represents the sixth consecutive year of resources growth at Lulo, the company said. Total production from Lulo to date has reached 200,000 carats, generating $426 million at an average price of $2,122 per carat.

The Lulo mine, in operations since 2015, is considered the world’s highest dollar-per-carat alluvial diamonds operation.

Lucapa has a 40% interest and the rest is held by Angola’s national diamond company (Endiama) and Rosas & Petalas, a private entity.

Angola is the world’s fifth diamond producer by value and sixth by volume. Its industry, which began a century ago under Portuguese colonial rule, is successfully lessening government regulations and restrictions in favour of a greater participation by private entities.

Lucapa’s shares closed at A$0.12 on Monday in Sydney, leaving the diamond miner with a market capitalization of A$33.25 million (about $22 million).