LONDON – When the largest rough diamond in more than a hundred years comes up for auction at Sotheby’s London on 29 June, it will be a major event – and for good reason. First, at 1,109 carats and roughly the size of a tennis ball, this historic stone would make any other gem look diminutive. Second, given that it has already been identified by the Gemological Institute of America as possessing exceptional quality and transparency, it might make other precious stones look a bit dull. So it stands to reason that the Lesedi La Rona, which means “our light” in Botswana’s Tswana language, will be offered at  a stand-alone sale, and that Sotheby’s jewellery division chairman David Bennett would call it “the find of a lifetime.” He adds, “No rough even remotely of this scale has ever been offered before at public auction.” 


THE 1,109-CARAT LESEDI LA RONA IS THE LARGEST GEM-QUALITY ROUGH DIAMOND DISCOVERED IN OVER 100 YEARS. ESTIMATE UPON REQUEST. PHOTOGRAPH BY DONALD BOWERS/GETTY IMAGES FOR SOTHEBY'S

Bennett’s words are no hyperbole: Unearthed last November in the Lucara Diamond Corporation’s Karowe mine in Botswana, the spectacular rough crystal provoked much astonishment and exultation as it emerged from the mass of mined material. The last time such  a momentous rough diamond was discovered dates back to 1905, when the 3,106.75-carat rough Cullinan Diamond was discovered at the Cullinan Mine near Pretoria, South Africa. Presented to King Edward VII two years later, it was subsequently cut, yielding nine polished diamonds of superb quality. One of them, the 530.20-carat Great Star of Africa, became the largest top-quality polished diamond in existence and was set into Queen Elizabeth II’s sceptre. The other eight all became part of the Crown Jewels of Great Britain. After holding the title of largest D colour diamond for nearly a century, the Great Star of Africa may soon have to relinquish it, as independent reports indicate that the Lesedi La Rona – although weighing less than the Cullinan in the rough – may have the potential to yield the new largest top-quality diamond that has ever been cut and polished.  

But we are getting ahead of ourselves. Rather than dream of what this superlative specimen could yield, we should think back to over three billion years ago, when it was first formed deep in the earth’s mantle, a result of the compression and crystallization of carbon under pressure from the rock above and the extreme temperatures at the earth’s core. Although its creation is hard to fathom, most people would readily recognise that a diamond of this size, with such extraordinary properties, is quite an astounding natural wonder. Perhaps more wondrous – some would even say miraculous – is that it made its journey to the earth’s surface and was discovered only just recently.  


THE “LESEDI LA RONA” WILL BE OFFERED AT SOTHEBY’S LONDON ON 29 JUNE 2016.
PHOTOGRAPH BY DONALD BOWERS/GETTY IMAGES FOR SOTHEBY'S

And if and when, after the sale, the time eventually comes to cut this spectacular rarity, a full complement of truly diamantine nerves will be required. For while the art and craft of diamond-cutting has radically improved since the Cullinan was cut, it is still through human ingenuity that the full beauty and light of a gem is revealed. Certainly, the laser scanning, plotting and precision-cutting used today were unimaginable a century ago, and our scientific understanding of the diamond’s optical properties has deepened. But the complex process of cutting diamonds remains intuitive, demanding experience and expertise as well as the ability to look into the heart of the stone; a generally high-stakes profession, it becomes especially charged in cases such as this one. According to the independent reports accompanying the Lesedi La Rona, the craftsman to whom the task of cleaving this stone befalls has the opportunity to cut what may potentially be the world’s largest top-quality diamond. 

Only time will reveal the gems the Lesedi La Rona will yield. For the moment, all we know is that its sale will be a milestone in the history of diamonds and auction house sales, if only because this once-in-a-lifetime rarity will be on centre stage.


Vivienne Becker is a jewellery historian and contributing editor for the Financial Times’s How to Spend It.

Lesedi La Rona will be on view in London from 18–20 and 25–28 June. Auction: 29 June, London. Enquiries: +44 207 293 6244.