Diamonds. Facts I never knew. Born by heat and pressure 3 billion years BC.

Diamonds were formed around 3.3 billion years ago under intense heat and pressure deep within the Earth’s crust (the outside layer), more than 150 km below the surface in a area known as the mantle (the part of the earth that surrounds its central core) which consists of volcanic magma (hot liquid rock). 

Diamonds are the hardest natural substance known to man. Made from pure carbon, a diamond can produce more brilliance (shine, great brightness of light or colour) than any other gemstone on earth. As testament (proof) to a diamond’s rarity, on average 250 tons of ore must be mined in order to produce a single carat gem quality polished diamond. Thus, only a small amount of diamond rough (uncut stone) makes it to the surface, and fewer still are of gem quality suitable for diamond jewelry. 

Diamonds are found at a depth of approx. 150-200km below the surface of the Earth. Here, temperatures average 900 to 1,300 degrees Celsius and at a pressure of 45 to 60 kilobars (which is around 50,000 times that of atmospheric pressure at the Earth’s surface). Under these conditions, molten lamproite (volcanic and sub-volcanic rocks) and kimberlite (commonly known as magma) are also formed within the Earth’s upper mantle and expand at a rapid rate. This expansion causes the magma to erupt, forcing it to the Earth’s surface and taking along with it diamond bearing rocks. Moving at an incredible speed, the magma takes the path with least resistance, forming a ‘pipe’ to the surface.

As it cools the magma hardens to form Kimberlite and settles in kimberlite pipes (vertical structure). These kimberlite pipes are the most significant source of diamonds, yet it is estimated that only 1 in every 200 kimberlite pipes contain gem-quality diamonds. 

The name ‘Kimberlite’ was derived from the South African town of Kimberley where the first diamonds were found in this type of rock.

Cullinan

Well, this is what happened to the superintendent, Frederick Wells when he was walking through the Premier Mine in South Africa.

On 26 January, 1905 during his routine inspection Frederick made an unexpected discovery changing the world of diamonds. It was on this historical day that he discovered the world’s biggest diamond.

The diamond was then named the Cullinan after the owner of the mine, Sir Thomas Cullinan, who was visiting the mine on that particular day.

After Frederick had made the discovery, the large Cullinan rough diamond was taken to the mine office to be weighed. To everyone’s surprise, the stone weighed in at a whopping 3 106 carats (a carat is a unit of weight for diamonds and other gemstones. One carat equals 200 milligrams or 0.200 grams), making it the largest diamond ever to be found. Many experts believe that the Cullinan diamond was only a fragment of an even bigger stone that still needed to be discovered.

This rumour caused sparks amongst the mining community, who hoped to find the other half of the stone.

The magnificent diamond was insured for R17 million (South African rand) before it was carefully transported to England. Here a Premier London agent named, Sigismund Neumann kept the large diamond for safe keeping. When they transported the large diamond, they had to take extreme measures to keep it safe. The Cullinan was sent in a plain box via parcel post while detectives from London were asked to transport a replica as a decoy publically. After the Anglo-Boer War, the Transvaal government bought the diamond for R2.4 million. The Cullinan was then presented to King Edward VII of the United Kingdom as a gift of goodwill on his 66th birthday in 1907.

The diamond was then entrusted to I. J. Asscher and Co (Royal Asscher Diamond Company, the company is responsible for cutting some of the most famous diamonds in the world. Its headquarters still stand at its original location Tolstraat 127 in Amsterdam, the Netherlands.) where it was divided in various large stones.

When the famous diamond cutter received the large diamond, he studied it for months. At first, it was difficult to cut the Cullinan, but after months of careful planning, Asscher divided the diamond into nine major stones, ninety-six smaller stones and about 19.5 carats of unpolished diamonds.

The two largest diamonds weighing 1 977 carats and 1 040 carats respectively in the rough. The two larger diamonds, known as the Cullinan I and Cullinan II, were given to King Edward VII.

The polished Cullinan I (530.20 carats) is the biggest stone of the nine diamonds and the polished Cullinan II (317.40 carats) the second most significant. Today the stone is also referred to as The Star of Africa (Cullinan I) and The Lesser Star of Africa (Cullinan II). 

Both of these breathtakingly beautiful stones are on display in the Tower of London as part of the Crown Jewels.

The Cullinan III is pear-shaped and weighs 94.40 carats. The diamond was originally an ornament on top of Queen Mary’s Crown. Today Queen Elizabeth II can be seen wearing the Cullinan IV as a pendant-brooch.

The Cullinan IV is a cushion shape diamond (cushion cuts diamonds are square or rectangular brilliant cuts with rounded corners and curved sides, a pillow-like shape) that weighs 63.60 carats. The stone was previously placed in the band of Queen Mary’s crown, but today it can be seen as the top part of Queen Elizabeth II’s pendant-brooch (as discussed above).

The Cullinan V is a triangular-pear shaped diamond and weighs 18.80 carats. First, it was worn as a brooch by Queen Mary but was then later used in the circlet of her crown as a substitute for the Koh-i-Noor (a famous colorless diamond that was found near Guntur, India). The Koh-i-Noor was utilized in the new crown for Queen Elizabeth in 1937. Today Queen Elizabeth II can be seen wearing it as a brooch.

The large Cullinan diamond that was discovered back in the 1900’s has indeed become part of history. Not only is it the largest gem-quality diamond ever discovered, but it’s also part of the world’s most classic jewelry pieces. The Cullinan, in essence, is remarkable and will continue to amaze throughout history.