Vancouver-based Lucara says it has recovered a 1,758ct diamond - bigger than the 1,109ct Lesedi La Rona diamond found in 2015, and the largest diamond taken from the mine to date.

Lucara described the newly recovered gem as one of the largest diamonds ever mined, and certainly the largest in Botswana. The unbroken diamond was recovered through Lucara's state-of-the-art XRT circuit, commissioned in April 2015.

Weighing close to 352g and measuring 83mm by 62mm by 46mm, the diamond has been characterised as near-gem of variable quality, including domains of high-quality white gem.

Lucara's XRT technology has to date recovered 12 diamonds larger than 300ct, including the two whoppers.

The Lesedi La Rona stone was sold to London-based Graff in 2017 for US$53 million, or $47,777/ct, and was earlier this month reduced into a 302.37ct square emerald cut diamond, the largest of its kind.

Lucara CEO Eira Thomas said the find affirmed the coarse nature of the Karowe mineralisation, and underscored the likelihood of recovering other large, high-quality diamonds in the future. The mine plan is designed to venture deeper into the orebody and gain access to the geologically favourable EM/PK(S) unit, the source of both of record-breaking 1,000ct-plus diamonds to date.

Lucara's (TSX:LUC) Toronto-quoted shares gained 11.39% or C18c at Thursday noon to $1.68, capitalising the company at $666.5 million.