The discovery

Found at the Lucara Karowe mine in Botswana, the 1,109 carat rough diamond was the largest gem quality rough diamond discovered in over 100 years and the second largest ever found.

“There is a huge amount of good fortune involved in unearthing a rough diamond of this extraordinary beauty and importance. Year after year can go by… month after month can pass… with nothing… then you get lucky,” says Laurence Graff of the discovery.

The record-breaking stone was given the name Lesedi La Rona, which means “Our Light” in Tswana, the official language of Botswana.

The acquisition

Laurence Graff was confident that buying the 1,109 carat Lesedi La Rona rough diamond would result in sensational polished gems, as he had already purchased a 373 carat rough diamond in May 2016 which was believed to have come from the same rough stone. Already familiar with the properties of this 373 carat diamond, he could predict how the Lesedi La Rona might behave similarly for his polishers.

Even with the experience gained from polishing the 373 carat diamond, the Lesedi La Rona presented a unique challenge to Graff’s expert gemmologists. They had never analysed a stone of such a prodigious size, which was too large for the existing equipment. A scanner had to be custom built specifically for the Lesedi La Rona with brand new imaging software capable of probing its vast expanses.

Using the highly sophisticated new technology, Graff’s gemmologists explored deep within the diamond, mapping the maze of imperfections and using this information to plot which cuts would yield the largest and highest clarity diamonds possible.

At first, the technical analysis of the Lesedi La Rona concluded that a 300 carat diamond simply wasn’t possible. However, with the extraordinary expertise surrounding the transformation of this historic rough stone, Laurence Graff was convinced that this exceptionally rare weight could be achieved, and from that moment onwards, the challenge was set.

Cutting and polishing

After many months of analysis, a plan was put in place for the cutting and polishing of the Lesedi La Rona that was so precise there was absolutely no room for error.

A rough diamond is a natural substance; a complex crystal with subtle nuances that only reveal themselves once the process begins. It was impossible to predict how long each stage – the initial cutting with precise lasers, followed by the shaping and faceting by Graff’s highly skilled diamond artisans – would take. It took hundreds of hours to polish the table facet – the largest facet at the top of the diamond – alone.

The results

By the time the final finessing of the diamond’s facets had taken place, more than 18 months had elapsed and the diamond had passed through the hands of a highly skilled team of gemmologists and master craftsmen sharing decades of experience.

Upon sending this masterpiece of technical audacity and diamond artistry to the GIA for certification, it was confirmed that Laurence Graff’s challenge had not only been met, but exceeded. The Graff Lesedi La Rona, as the principal polished diamond would be known from now on, weighs an awe-inspiring 302.37 carats and is a top D colour. It is not only the largest square emerald cut diamond in the world but also the largest highest clarity diamond ever graded by the GIA.

Alongside the Graff Lesedi La Rona, a total of 66 “satellite” diamonds have also been polished from the world-famous rough diamond, ranging in size from under a carat to in excess of 26 carats.