MINING

Operational overview

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Letšeng Diamond Mine

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Ghaghoo Diamond Mine

Letšeng Diamond Mine

The Letšeng mine is located in the Maluti Mountains of Lesotho and is renowned for its recovery of large, high quality, exceptional Type II diamonds.

Among these diamonds recovered are the 910 carat “Lesotho Legend”, the 603 carat “Lesotho Promise”, the 550 carat “Letšeng Star” and the 493 carat “Letšeng Legacy”.

Letšeng has also produced high-quality pink and blue diamonds, with a rare blue diamond achieving a sales price of US$603 047 per carat in 2013 and an exceptional pink diamond achieving US$656 934 per carat in 2019.

Letšeng ranks in the top 10 global diamond producers by revenue. The large high value greater than 100 carat diamonds from Letšeng account for 70% to 80% of the Group’s revenue annually.

Letšeng has grown to be one of the largest open pit diamond mines in the world, processing ore from two kimberlite pipes, the Main pipe 17.0ha and the Satellite pipe 5.2ha. In 2017, certain Business Transformation initiatives were undertaken to unlock additional value at Letšeng, which included an updated open-pit life of mine plan, large diamond recovery and reduced diamond breakage initiative projects, and a mining optimisation project.

For more information on Letšeng, please refer to the latest:

Ghaghoo Diamond Mine

The Ghaghoo mine, situated near the south-eastern border of the Central Kalahari Game Reserve was acquired by Gem Diamonds in May 2007 with a 25-year mining licence obtained from January 2011. The mine consists of a 10.4ha kimberlite pipe, and has an in situ value of US$4.9 billion (as at 1 January 2014). Diamonds produced at Ghaghoo are of a commercial quality and lower value and size than those from Letšeng.

The Ghaghoo mine, the first underground diamond mine in Botswana, was placed on care and maintenance in 2017 following the weak state of the diamond market for the category of diamonds produced at Ghaghoo and a decision was made to proceed with the sale of the Ghaghoo mine.

During the first six months of 2018 a formal sale process to sell the Ghaghoo mine commenced with Nedbank Capital being appointed as the corporate advisor on the transaction. The sales process continues.

For more information on Ghaghoo, please refer to the latest:

FROM MINE TO MARKET

Sales and Marketing

Gem Diamonds continues to invest in its sales, marketing and diamond analysis operations to pursue ways of maximising revenue through a combination of marketing channels, including tenders, strategic partnerships and extractions for manufacturing to capture additional margins further along the diamond pipeline.
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From Letšeng mine

The Letšeng mine produces large, exceptional quality diamonds which supply the very top end of the diamond market.

Letšeng’s top-quality diamonds are sent from Lesotho to Baobab Technologies in Antwerp for analysis to achieve the greatest returns at each of the diamond tenders.

Rough diamond analysis

Baobab Technologies

Baobab Technologies’ advanced mapping and analysis of Letšeng’s top-quality rough diamonds assists in assessing appropriate true values of these rough diamonds before they are presented for sale.

This in-depth knowledge provides the basis for setting robust reserve prices for each of the high value diamonds at each tender and assists in making strategic selling, partnering or manufacturing decisions.

Sales and marketing services

Gem Diamonds benefits from actively managing its own multi-channel marketing strategy and by establishing and developing relationships with new and existing clients.

Gem Diamonds maximises revenue from its rough diamonds through a combination of channels, which includes tenders and partnerships, in addition to pursuing additional initiatives further down the diamond pipeline.

Polished diamonds are sold through direct selling channels to prominent high-end diamantaires.

Market

Gem Diamonds’ client base consists of prominent high end diamantaires and manufacturers from the world’s major diamond centers: Belgium, India, Hong Kong, Israel, New York and Dubai.

MINING

Resources and Reserves

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Letšeng Diamond Mine

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Ghaghoo Diamond Mine

Letšeng Diamond Mine

The Letšeng kimberlites are unique and have been a source of intrigue for geologists since their discovery. Not only are the diamond populations atypical, but the way the pipes were formed, and their emplacement history is unusual. Several features of the two Letšeng pipes (Main and Satellite) differentiate them from the Kimberly-type Pyroclastic Kimberlites and impact our understanding of the complex distribution of diamonds within the pipes.

Since mid-2013, the geological team at Letšeng has been working with a team of leading kimberlite experts from Canada and South Africa to gain a deeper understanding of the relationships between the various kimberlite types within each pipe and to differentiate the higher grade varieties from those with high value (containing large and abundant Type II diamonds).

Although Letšeng demonstrates broad scale consistency year on year in terms of price and average stone size for each of the kimberlite domains, the objective of the resource development programme is to gather data on local variability within each domain to improve large stone predictability and calibrate expectations of what each domain and subdomain can reasonably be expected to yield in terms of grade, average stone size, number of +100 carat stones and average price.

No additional resources and reserves have been added since the last update carried out by Venmyn Deloitte in 2015. The priority of the geological team is to firm up on the existing resource base and make appropriate operational and infrastructural adjustments to extract maximum value.

A core drilling programme is currently underway at Letšeng and is scheduled to be completed towards the end of 2021. New 3D geological models will then be updated and a revised Resource and Reserve Statement with supporting technical report is scheduled to be issued in 2022.

Ghaghoo Diamond Mine

Since mid-2013, the geological team at Letšeng has been working with a team of leading kimberlite experts from Canada and South Africa to gain a deeper understanding of the relationships between the various kimberlite types within each pipe and to differentiate the higher grade varieties from those with high value (containing large and abundant Type II diamonds).

Owing to the decline in prices for the Ghaghoo diamonds, it became apparent that the sustainability of the mine, in its current form, was not financially viable. No further resource evaluation work was carried out at Ghaghoo during the commissioning and ramp-up phases before the decision was taken to place the mine on care and maintenance. Consequently, there has been no update to the Resource and Reserve statement published by Venmyn Deloitte in 2014.

Technology and Innovation

 

Diamond damage is ubiquitous among producers of larger high-value gem diamonds. Furthermore, the Letšeng mine has a unique diamond distribution with a significant portion of its revenue held in the +5mm fraction (greater than two carats).

The Group has been working to mitigate the impact of diamond damage on Letšeng’s production for many years. While incremental improvements have been achieved through optimising operating practices and various technological enhancements, tweaking conventional technology will not realise the step changes required to significantly reduce diamond damage.

The potential changes for significantly improving revenue through reducing diamond damage are:

  • the early identification of liberated diamonds;
  • identification of diamonds within kimberlite; and
  • a non-mechanical means of liberating these diamonds within kimberlite.

Gem Diamonds has made significant progress on the identification, validation and testing of technologies from various industries to complement its innovation drive of early detection and non-mechanical means of liberating diamonds.

 

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Diamond
detection

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Diamond
liberation

Diamond detection

Gem Diamonds successfully validated the detection of diamonds within kimberlite using scanning technology in conjunction with proprietary imaging and sorting algorithms. Two types of technologies are under investigation with varying degrees of detection potential, scalability and investment required. The proof of concept plant construction at Letšeng has highlighted various impediments and opportunities that need to be addressed and considered to enhance the operation of the technology employed.

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Diamond liberation

Once a diamond has been identified within the kimberlite, the next step is to liberate this diamond without causing any damage. A non-mechanical liberation unit was developed inhouse, that utilises high voltage pulse power for the selective fragmentation of composite materials, as a means of liberating the encapsulated diamonds. Testing of this unit at Letšeng mine commenced in the beginning of 2018, at altitude, with substantial progress made throughout the year.

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  • D

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