Shirley Bassey sang Diamonds Are Forever and she might very well be right when it comes to the Enigma diamond. The Enigma is a carbonado type black diamond and is the largest cut diamond in the world according to Guinness World Records, weighing a very impressive 555.55 carats or 111 grams with 55 faces.
While most diamonds such as the world's biggest rough diamond – the Cullinan – are found deep within the Earth’s surface in igneous kimberlite rock, the Enigma has many competing theories about its origin, with some suggesting that it was carried onto the Earth’s surface by a meteorite. This is because carbonado diamonds contain the mineral osbornite, which is only found in meteors, suggesting the diamond originates in outer space.
These black diamonds are thought to be around 2.6 to 3.8 billion years old, and have only ever been found in Brazil and the Central African Republic. This is thought to be because at this time in the Earth’s history, the west coast of African and modern day Brazil may have been fused into a supercontinent in a similar manner to Pangea or Gondwanaland.
These stones are a “polycrystalline or aggregate diamond material” according to the International Gem Society and contain amorphous carbon, diamond, and graphite. They are found in alluvial sedimentary rock deposits only. This makes them considerably more durable than regular crystalline diamonds, and because of this the diamond is said to have taken three years to cut and polish into its 55 facets.
Researchers suggest that carbonados are formed within supernova explosions and their unusual properties are formed before they reach Earth, while others suggest that the impact of the material landing into Earth’s surface caused these extraordinary stones to form.
The Enigma diamond was bought at a Sotheby’s auction for $4.3 million (£3.16 million) in February 2022.
While Sotheby’s did not disclose the buyer, the entrepreneur Richard Heart announced on social media that he had purchased the diamond using cryptocurrency and renamed it the Hex.com diamond after his cryptocurrency business.