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World’s second-largest diamond ever recorded unearthed at Botswana mine

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World’s second-largest diamond ever recorded unearthed at Botswana mine
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From the June/July 2019 Pick & Shovel Gazette

By Alix M. Barnaud


If the odds are in its favor, a mining company is lucky to find one sizeable diamond throughout its exploration.

However, for the Lucara Diamond Corp., sheer luck cannot solely be held responsible for such findings anymore. On April 25, 2019, the Canadian company announced the discovery in its Botswana mine of the second-largest diamond ever recovered. The astounding 1,758-carat unbroken stone measures 83mm x 62mm x 46mm — bigger than a tennis ball — and weighs approximately 352 grams. According to the company's news release, "the diamond has been characterized as near gem of variable quality, including domains of high-quality white gem.”

As impressive as it is, the diamond is still significantly smaller than the stone that remains known as the largest diamond ever recovered. The Cullinan diamond, also called the Star of Africa, was discovered in South Africa in 1905. With an original weight of 3,106.75 carats, it is still a long way from being dethroned. The Cullinan has since been cut into several stones, some of which are part of England's crown jewels.

However, it is not the first time that Lucara Diamond Corp. recovered a record-breaking diamond. The aptly named Karowe mine, which means “precious stone” in the local language and is 100 percent owned by the corporation, has also produced several other huge diamonds, including the previous holder of the title of second-largest uncut diamond in the world. The Lesedi La Rona, which means "Our Light" in Tswana dialect, weighed 1,111 carats and measured 65 mm × 56 mm × 40 mm. It was recovered on Nov. 16, 2015. Another remarkable diamond produced by the Karowe mine was the Constellation, an 813-carat stone that sold for a staggering $63 million in 2016, a world-record sale for a rough gem.


Botswana: a promised land for large-sized diamonds

Botswana is a relative newcomer in the world of diamond extraction. However, the country is quickly becoming one of the forces to be reckoned with on the market. Once one of the poorest countries in the world after it gained its independence from Britain in 1967, Botswana is now among the most prosperous countries in Africa thanks to the presence of such stones on its territory.

The scenario might have been very different if it were not for the De Beers company, originally from neighboring South Africa and one of the leading sellers of "rough stones" in the world. After a careful exploration of the geology of the region and a thorough program of reconnaissance soil-sampling, the company struck gold (or, rather, diamonds) in two clusters: a large one in the southeast of the country and a smaller one in the northeast.

Before the early 1970s, the systematic exploitation of gemstones was virtually unheard of in Botswana. And yet, since the first mines opened in 1971, the country has provided 665 million carats, which represents 14 percent of all diamonds ever produced in the world, almost the same as South Africa, which has produced 680 million carats since 1870. Among other recent significant diamond news, Botswana also produced the second-largest blue diamond ever uncovered, which was unveiled by the Okavango Diamond Company in April 2019. Although smaller than the largest blue diamond in the world — the famed Hope Diamond, which weighs 45.52 carats — the 20.46 “Okavango Blue” stands out by its exceptional clarity and has been graded by the Gemological Institute of America (GIA) as” Very, Very Slightly Included," or VVS2, meaning inclusions "are difficult for a skilled grader to see under 10x magnification." In comparison, the Hope Diamond is classified as "Very Slightly Included," or VS1 grade, meaning "inclusions are minor and range from difficult to somewhat easy for a skilled grader to see under 10x magnification."

However, Botswana's involvement is not limited to the production of diamonds. De Beers has shifted its rough diamond trading operation from its historic location in London to Gaborone, the capital of Botswana.  The move includes the opening of the largest, most technologically advanced diamond sorting complex in the world, employing 600 people and owned at 50 percent by the local government. Unlike many other African countries where such riches can be found, the local authorities have always been heavily involved in the diamonds’ mining, allowing the economy to thrive and the development of infrastructure such as roads, hospitals, and schools.


A little help from technology

Another factor that contributed to the recovery of such diamonds is the constant progress of technology. Unearthing large diamonds without breaking them in the process has been an issue for centuries. In its news release, Lucara’s CEO Eira Thomas credited the recent discoveries in large part to the company’s investment in high-tech recovery methods: “Lucara’s technologically advanced, XRT diamond recovery circuit has once again delivered historic results. Karowe has now produced two diamonds greater than 1,000 carats in just four years, affirming the coarse nature of the resource and the likelihood of recovering additional, large, high quality diamonds in the future, particularly as we mine deeper in the orebody and gain access to the geologically favorable EM/PK(S) unit, the source of both of our record-breaking, +1,000 carat diamonds." In addition to the two diamonds above 1,000 carats, Karowe has produced 12 diamonds above 300 carats since the XRT sorters were installed, 50 percent of which were categorized as gem quality.

The XRT technology mentioned by Thomas is a single-stage alternative to traditional concentration and recovery techniques used in the diamond mining industry and is produced by the Norwegian company TOMRA Sorting Mining. Its sensor-based technology detects the carbon in the ore through an X-ray machine, eliminating the need for potentially damaging traditional methods such as explosions to extract the ore, followed by crushing machines to break it down further. The latest discovery “highlights the success of TOMRA Sorting technology, which has detected four of the top ten largest diamonds in the world to date” according to a TOMRA statement from April 26, 2019. Besides, the sensor-based sorters could help reduce the mining industry’s significant energy consumption by 15 percent, as well as reduce the amount of water used by three to four cubic meters per ton of ore.

With such success, it is no surprise that TOMRA has been busy installing its machines all over the world, including other African countries like Lesotho and Sierra Leone, but also Russia, Canada, and Brazil among others. We could very well see more record-breaking stones coming out in the next couple of years.


Size isn’t everything

Although gems of such astonishing proportions are sure to bring the attention of potential buyers, their size does not necessarily determine their market value, as Lucara recently found out itself. After the record-breaking sale of the 813-carat Constellation diamond for $63 million in 2016, the larger, 1,109-carat Lesedi La Rona was expected to reach sums never seen before on the market. Some estimates were reaching upward of $90 million, with $70 million being the generally expected sale price. However, the Lesedi La Rona failed to sell during its first public, standalone auction at Sotheby’s in 2016, an unusual setup for a rough diamond. The bids stalled at $61 million, failing to reach the reserve price. It eventually sold to London jeweler Laurence Graff more than a year later for $53 million in a private sale.

The latest supersized diamond's market value remains to be seen. The market for this type of stone is limited. More than the size, the quality of the gem — including its color, clarity, and the cutting possibilities — is what makes or breaks the value of a rough diamond. Until the analysis is complete, little can be said about the sale potential of the stone. However, experts estimate that its quality is lower than the Constellation or Lesedi La Rona, the “near gem” denomination indicating that the large diamond may produce very little gem quality faceted.

Although the market value of this particular diamond may not reach record levels, its sheer size and the number of large diamonds recently recovered demonstrates the advances of technology and the potential for more oversized stones to be recovered in the near future, in Botswana and elsewhere. For any gem aficionado, it is undoubtedly an exciting time to be alive. 


Alix M. Barnaud is a travel writer based in Portsmouth, New Hampshire.


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