Editor’s Note
This week, Botswana unveiled the world’s second-largest rough diamond ever discovered—a remarkable 2,492-carat stone. While uncut and unpolished, its sheer size and weight make it a geological marvel.
Botswana’s soil revealed this week the world’s second largest rough diamond: 2,492 carats. An exceptional discovery.
For now, as it is neither cut nor polished, the world’s second largest diamond ever discovered mostly resembles a huge, vaguely transparent but somewhat dull stone, about the size of a very large avocado. If you held it in your hand, you would certainly feel its weight! It weighs nearly 500 grams. In other words, 2,492 carats (this is the unit used to measure the mass of gemstones. One carat = 0.2 grams).
We are 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 was cut into nine different stones, some of which are set in the Crown Jewels.
The one found this week does not yet have a name but, according to sources cited by the Financial Times, it is worth at least 40 million dollars. When it finds a buyer, the sale revenue will be shared between the company operating the mine, the Canadian Lucara Diamond Corporation, and the state of Botswana, one of the largest diamond-producing countries, which alone accounts for 20% of global production.
Botswana, located in Southern Africa, is traversed by the vast Kalahari Desert which it shares with South Africa and Namibia. Exceptional pieces are increasingly found there. For example, five years ago, a 1,758-carat stone was extracted from the same Karowe mine.
Today, to find stones that formed in the molten rock of the Earth’s mantle and were then brought up by volcanic eruptions, X-rays are used. This is what Lucara has been doing since 2017, for example. Once the sensor detects the diamond, a very powerful and precise jet of compressed air is sent towards the stone, ejecting it from its surroundings, naturally separating it from rubble and other minerals. This causes less damage, thus preserving its original size. Therefore, it can be sold for much more.
To not miss out on this windfall and maintain control over this resource, which accounts for almost one-third of its GDP, the Botswana government renegotiated last year the agreement linking it to mining companies, primarily De Beers. Its share, initially 25%, increased to 30%. It will increase further to reach 50% within ten years.