Featured in the “Hong Kong Jewels and Jadeite” sale, the unheated gemstone carries an estimate of HK$3 million to HK$5m (c. £305,000 to £510,000).

Unearthed in Mozambique in 2003 as an 830-carat rough crystal by gem hunter Don Kogen, the stone is named after his wife, jewellery designer Kat Florence. After initially being cut to 315 carats, the gem displayed undesirable “windowing”, a flatness affecting its brilliance. Following meticulous recutting by Ms Florence’s team to enhance its fire, the tourmaline achieved its current weight, National Jeweler reports.

Described as the largest known unheated Paraíba-type tourmaline of its vivid saturation and masterful cut, the “Kat Florence Lumina” is recognised for its exceptional combination of size, colour, clarity, and cut. Its quality is attested by reports from Bellerophon Gemlab, AGL, and Gübelin Gem Lab.

Prior to the auction, the exceptional gemstone will be exhibited in Taipei (11-13 April), Singapore (10-11 May), and Hong Kong (17-21 May).