How Botswana unearthed the world’s second largest diamond

The land of Botswana this week revealed the second largest rough diamond in the world: 2,492 carats. An exceptional discovery.

For now, since it is neither cut nor polished, the second largest diamond in the world ever discovered looks more like a huge, vaguely transparent but slightly dull pebble, the size of a very large avocado. If you had it in your hand, you would feel its weight! It weighs almost 500 grams. In other words, 2,492 carats (this is the unit with which the mass of precious stones is measured. One carat = 0.2 grams).

It is not far from the world record, the Cullinan, 3,100 carats, discovered in South Africa in 1905, when the country was still a British colony. The Cullinan had been cut into nine different stones, some of which were set in the Crown Jewels.

The one found this week does not yet have a name but, according to sources cited by the Financial Timesit is worth at least $40 million. When it finds a buyer, the proceeds from the sale will be shared between the company that operates the mine, the Canadian Lucara Diamond Corporation, and the state of Botswana, one of the world’s largest diamond producers, which alone accounts for 20% of global production.

Botswana, located in southern Africa, is crossed by the immense Kalahari Desert that it shares with South Africa and Namibia. Exceptional pieces are increasingly often found there. Five years ago, for example, a 1,758-carat stone was extracted from the same Karowe mine. Sold to Louis Vuitton (for an undisclosed price).

Today, to find stones that were formed in the molten rock of the Earth’s mantle and then brought up by volcanic eruptions, we use X-rays. This is what Lucara has been doing since 2017, for example. Once the sensor detects the diamond, a very powerful and very precise jet of compressed air is sent towards the stone, which ejects it from its environment, naturally separating it from rubble and other minerals. This allows it to be damaged less, and therefore to keep its original size. And therefore to sell it for a much higher price.

In order not to miss out on this windfall and to maintain control of this resource, which accounts for almost a third of its GDP, the Botswana government renegotiated last year the agreement that binds it to mining companies, mainly De Beers. Its share, initially 25%, has increased to 30%. It will increase to 50% within ten years.