Diamond miner Lucapa Diamond Company (ASX: LOM) has unearthed a massive 128-carat diamond from its flagship Lulo alluvial mine in Angola, making it the twelfth sparkler measuring over 100ct recovered from the field to date.

The stone has been confirmed as a top-colour white Type IIa diamond and was discovered among Specials recovered recently from Mining Block 6 in the prolific Lulo diamond field, including a 7.5ct fancy purple pink gem.

This is great news for Lucapa, which earlier this month reported netting US$16.7 million (A$22.9 million) in a historic tender of seven large, top-quality Lulo diamonds, at an average price of US$33,530 per carat.

Together with its Lulo joint venture partners Empresa Nacional de Diamantes and Rosas & Petalas, Lucapa said it will include these latest discoveries in the next international tender, along with a 75ct Type IIa top-colour diamond recovered late last year and other special gems.

Earlier this month, the joint venture partners announced plans to further expand production at Lulo by more than 25% in 2019.