Diamonds are the hardest natural substances on earth. They are formed over a period of a billion or more years , deep within earth’s crust – about 150km (90 miles) deep – and are pushed to the surface by volcanoes. Most diamonds are found in volcanic rock, called Kimberlite, or in the sea after having been carried away by rivers when they were pushed to the surface.
A diamond is 58 times harder than the next hardest mineral on earth, corundum, from which rubies and sapphires are formed.
The largest diamond
The world’s largest diamond was the Cullinan, found in South Africa in 1905. It weighed 3,106.75 carats uncut. It was cut into the Great Star of Africa, weighing 530.2 carats, the Lesser Star of Africa, which weighs 317.40 carats, and 104 other diamonds of nearly flawless color and clarity. They now form part of the Crown Jewels.
The Cullinan was three times the size of the next largest diamond, the Excelsior, which was also found in South Africa. Another diamond that also took 3 years to cut, and also is part of the Crown Jewels, is the Centenary Diamond. It weighs 273.85 carats and is the world’s largest flawless diamond.
The biggest diamond in the entire universe is thought to be Lucy, a crystallized white dwarf star, a star consisting of diamonds. It’s weight is 10 billion trillion trillion carat. Named after the Beatles song, Lucy in the Sky with Diamonds, it is technically known as BPM 37093.