The Real Story Behind How the World's Largest Rough Diamond Was Cut for the Queen's Crown Jewels

The historic legal agreement that arranged for the cutting of the world's largest diamond is being auctioned later this month

The story behind the cutting of the world’s largest gem-quality rough diamond that helped create Queen Elizabeth’s Crown Jewels has been unearthed in rare documents.

The original 3,106-carat Cullinan Diamond, which is still the largest ever discovered, was cut in Amsterdam and created an astonishing nine principal stones.

The main one, Cullinan I, is still the largest polished white diamond in the world, weighing 530.20 carats and is positioned on top of the Sovereign’s Sceptre, while Cullinan II, which weighs 317.40 carats, is set at the front of the Imperial State Crown.

Now, the historic legal agreement that arranged for the cutting of the world’s largest diamond is being auctioned later this month. Bonhams is selling the original manuscript copy, dated January 29, 1908, of the “Agreement for the Inspection of the Cullinan Diamond” between the representatives of King Edward VII and London diamond brokers M.J Levy & Nephews.

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Hulton Archive/Getty
<a href="" data-inlink="true">Queen Elizabeth</a> II's diamond jubilee galleries revealed, Westminster Abbey, London, UK - 29 May 2018
Nils Jorgensen/REX/Shutterstock

Alongside the original documents is a paste replica of the Cullinan in its original rough crystal form and two replica sets of the nine principal diamonds cut from the uncut diamond. The lot is estimated to fetch between $2,500-$3,800 in the sale on April 30.

Emily Barber, Director of Jewelry at Bonhams UK, said, “We are delighted to bring to auction this remarkable lot that is steeped in history and that tells the story of the cutting of the legendary Cullinan Diamond.”

Cullinan Diamonds
Cullinan Diamonds
Cullinan Diamonds
Cullinan Diamonds

The original rough diamond was discovered in 1905 near Pretoria, South Africa and named after Thomas Cullinan, chairman of the mine where it was found. The huge diamond was eventually sold for around $194,000 to the South African Transvaal Colony government, which then gave it to King Edward VII for his 66th birthday in November 1907.

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Crown Jewels of England. GraphicaArtis/Getty

Edward VII was then advised to have it cut and the renowned Asscher Company in Amsterdam were given the commission. The job of cleaving the diamond fell to Joseph Asscher, who studied it in detail before creating a 6.5mm deep incision in it over several days. But his first attempt in February 1908 at cleaving — or sawing — the diamond ended when the blade of his tool broke on impact when he struck the stone.

He then had to create stronger tools to do the job and the following week successfully split it into two parts, weighing 1,977 carats and 1,040 carats.

Cullinan Diamonds
Cullinan Diamonds

Over the following months, these diamonds were further polished and cut to create nine main stones, 96 smaller diamonds, and a quantity of polished of cuts or what is known as ends.

Bids can be made via Bonhams’ website, telephone, in writing, and in person on the day of the sale, April 30.

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