Lesedi La Rona May Once Have Been 2,774ct.

RAPAPORT... The second-largest diamond in history was probably twice as big before it broke into pieces, researchers at the Gemological Institute of America (GIA) have claimed.Similarities between the 1,109-carat Lesedi La Rona, the 812-carat Constellation and three other stones suggest they were all one large piece of rough weighing at least 2,774 carats beforevolcanic eruptions or mining processes split them up, the GIA said this week.Lucara Diamond Corp., which discovered all five diamonds atits Karowe mine in Botswana in November 2015, had already claimed that one ofthem, a 374-carat stone, was once attached to the Lesedi La Rona.The GIA last year studied three of the other stones - the Constellation, as well as diamonds weighing 296 carats and 183 carats- and speculated that they were also from the same rough. The theory was strengthened after the GIA gained access to faceted diamonds from the Lesedi La Rona and the 374-carat stone earlier this year, Dr. Ulrika D'Haenens-Johansson, a senior research scientist at the GIA, told Rapaport News Wednesday.The five diamonds had similar visual characteristics intheir rough form, and came from the same part of the Karowe mine at the sametime. They also gave results under close gemological analysis that were sosimilar that it's unlikely they were unrelated, Dr. D'Haenens-Johansson said. The nature of someof the stones' surfaces also suggested they had become detached from eachother."After the 2017 study, all we could do was speculate thatall five stones were from the same rough," she added. "Afterhaving the opportunity to examine all five stones in 2018, we are able to reachstronger conclusions. It is probable that there are other unaccounted piecesthat would have been part of this historic rough."Lucara CEO Eira Thomas said the company had no reason todisagree with the GIA's findings. Evidence indicates the larger stone broke upboth because of natural effects and being knocked around during the recovery process,Thomas noted.The company used X-ray transmission (XRT) technology to helpit recover the five large diamonds. It has since installed additional XRTequipment at Karowe to ensure it unearths exceptional stones as early aspossible in the process.D'Haenens-Johansson presented the findings at the GIA'sInternational Gemological Symposium in Carlsbad, California, in October, andpublished a summary in the Fall 2018 issue of Gems & Gemology, theinstitute's quarterly journal. The institute is preparing a full, peer-reviewedarticle in a forthcoming edition of the publication. Lucara sold the 374-carat diamond to Graff for$17.5 million in May 2017, and subsequently sold the Lesedi La Rona to thesame company for $53 million in September of that year. Graff recently unveiledseveral polished diamonds it had cut from the 1,109-carat rough.The Constellation went for $63.1 million in 2016 to apartnership comprising Dubai-based Nemesis International and Swiss jeweler DeGrisogono.Image: The Lesedi La Rona. (Donald Bowers/Getty Images/Sotheby's).