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Lesedi La Rona May Once Have Been 2,774ct.
Dec 20, 2018 5:43 AM
By Joshua Freedman
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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 before
volcanic eruptions or mining processes split them up, the GIA said this week.
Lucara Diamond Corp., which discovered all five diamonds at
its Karowe mine in Botswana in November 2015, had already claimed that one of
them, 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 in
their rough form, and came from the same part of the Karowe mine at the same
time. They also gave results under close gemological analysis that were so
similar that it’s unlikely they were unrelated, Dr. D’Haenens-Johansson said. The nature of some
of the stones’ surfaces also suggested they had become detached from each
other.
“After the 2017 study, all we could do was speculate that
all five stones were from the same rough,” she added. “After
having the opportunity to examine all five stones in 2018, we are able to reach
stronger conclusions. It is probable that there are other unaccounted pieces
that would have been part of this historic rough.”
Lucara CEO Eira Thomas said the company had no reason to
disagree with the GIA’s findings. Evidence indicates the larger stone broke up
both because of natural effects and being knocked around during the recovery process,
Thomas noted.
The company used X-ray transmission (XRT) technology to help
it recover the five large diamonds. It has since installed additional XRT
equipment at Karowe to ensure it unearths exceptional stones as early as
possible in the process.
D’Haenens-Johansson presented the findings at the GIA’s
International Gemological Symposium in Carlsbad, California, in October, and
published a summary in the Fall 2018 issue of Gems & Gemology, the
institute’s quarterly journal. The institute is preparing a full, peer-reviewed
article 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 the
same company for $53 million in September of that year. Graff recently unveiled
several polished diamonds it had cut from the 1,109-carat rough.
The Constellation went for $63.1 million in 2016 to a
partnership comprising Dubai-based Nemesis International and Swiss jeweler De
Grisogono.
Image: The Lesedi La Rona. (Donald Bowers/Getty Images/Sotheby’s).
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Tags:
Botswana, Gemological Institute of America, gemology, gems & gemology, GIA, Graff, Joshua Freedman, large diamonds, Lesedi La Rona, lucara, Lucara Diamond Corp., mining, Rapaport News, technology, XRT
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