The oldest diamond pipe in the world is located in the town of Cullinan in Gauteng Province, South Africa. An interesting way to experience this active diamond mine is to opt for a premier diamond tour. Available throughout the week, this is a surface tour of about two hours covering a diamond display room where you can get to see replicas of famous diamonds, a mock up underground tunnel, shafts which carry workers and rocks and the area where the Cullinan diamond was found.
The tour starts with a video that gives a brief history about the town’s diamond mining which began in 1903. The mine became famous two years later on January 26, 1905, when the Cullinan diamond weighing 3106 ct was found. What makes this diamond unique is that it is the world’s largest diamond. This rough diamond was named after Thomas Cullinan, who founded the mine.
The Transvaal Government decided that such a rare precious stone would make a sparkling 66th birthday present for King Edward the VII and posted it to him. This diamond was cut into nine major pieces and 96 small ones. The biggest cut piece is called the great star of Africa and adorns the royal sceptre. It weighs 530 ct. The second biggest cut piece called the lesser star of Africa is part of the British royal crown and weighs 317 ct.
One has to walk through this South African town to get to the mine. At the Presbyterian Church, which is the oldest church to be built, every Sunday mass is conducted. The houses across the church were used as residences for managers in 1907 and today operate as security and HR offices. Cafes, restaurants and curio shops line the street leading to the mine, which operates 24 hours with three shifts. Nearly 4500 ct of diamonds are produced every day. Of these, 20 per cent are gem quality diamonds and 80 per cent industrial quality.
Onsite visitors are taken to the diamond display room where synthetic or industrial replicas of world famous diamonds are on display. One gets to learn about the different types of Kimberlite rock in which diamonds are found. While brown Kimberlite is the oldest and is intruded first, grey Kimberlite forms 65 per cent of the ore body. Cullinan diamond mine has black Kimberlite, which is intruded last and it has to be crushed first before diamonds can be extracted from it.
At a time, 350 personnel work for a shift of eight hours for five days at the mine which employs a total of 4,000 workers. Out of the 750 km of tunnels inside the mine, currently only 66 km is being used. The next stop on the tour is a mock up underground tunnel measuring 4m x 4m, which is supported by a mixture of cement and concrete. The pipes inside are used for industrial water, compressed air, ventilation and drinking water. The temperature in these tunnels is 5 degrees cooler than what it is at the surface.
Since the mine does not conduct open cast mining but conducts underground mining, separate shafts have been installed for entry and exit of workers and to hoist rocks to the surface. The shaft for workers goes to a depth of 763 m and can carry 80 workers at a time in its elevator cage. It travels at a speed of 4 m per second. The tour ends at the diamond cutting shop where one can buy a diamond to take home with a Cullinan star cut.