Diamond
Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. At room temperature and pressure, another solid form of carbon known as graphite is the chemically stable form, but diamond almost never converts to it. Diamond has the highest hardness and thermal conductivity of any natural material, properties that are utilized in major industrial applications such as cutting and polishing tools. They are also the reason that diamond anvil cells can subject materials to pressures found deep in the Earth.
Cullinan Diamond
The Cullinan Diamond was the largest gem-quality rough diamond ever found, weighing 3,106.75 carats (621.35 g), discovered at the Premier No. 2 mine in Cullinan, South Africa, on 26 January 1905. It was named after Thomas Cullinan, the mine's chairman. In April 1905, it was put on sale in London, but despite considerable interest, it was still unsold after two years. In 1907, the Transvaal Colony government bought the Cullinan and presented it to Edward VII, King of the United Kingdom, who had it cut by Asscher Brothers in Amsterdam.
Argyle diamond mine
The Argyle Diamond Mine is a diamond mine located in the East Kimberley region in the remote north of Western Australia. Argyle is the largest diamond producer in the world by volume, although due to the low proportion of gem-quality diamonds it is set to close by 2020. It is the only known significant source of pink and red diamonds, producing over 90% of the world's supply. It additionally provides a large proportion of other naturally coloured diamonds, including champagne, cognac and rare blue diamonds. On June 21, 2015, after more than 11 years and 42 kilometres of tunnelling, the Argyle underground block cave development was officially completed. In 2013, Argyle is estimated to produce 10.2 million carats with an average per carat price of $25/carat.
List of diamonds
A number of large diamonds have gained fame, both as examples of the beautiful nature of diamonds and because of the famous people who wore, bought, and sold them. A partial list of famous diamonds in history follows.
Excelsior Diamond
The Excelsior Diamond is a gem-quality diamond, and was the largest known diamond in the world from the time of its discovery in 1893 until 1905, when the larger Cullinan Diamond was found. It was found on June 30, 1893 at the Jagersfontein Mine in South Africa, 130 kilometres south east of Kimberley whose fame as a diamond mining center always overshadowed that of Jagersfontein. It had a blue-white tint and weighed 971 old carats or 995.2 metric carats. The Excelsior rates as the third largest rough diamond of gem quality ever found. It was ultimately cut into ten stones weighing from 13 to 68 carats..
Premier Mine
The Premier Mine is an underground diamond mine owned by Petra Diamonds in the town of Cullinan, 40 kilometres (25 mi) east of Pretoria, Gauteng Province, South Africa. Established in 1902, it was renamed the Cullinan Diamond Mine in November 2003 in celebration of its centenary. The mine rose to prominence in 1905, when the Cullinan Diamond – the largest rough diamond of gem quality ever found – was discovered there. The mine has produced over 750 stones that are greater than 100 carats (20 g) and more than a quarter of all the world's diamonds that are greater than 400 carats (80 g). It is also the only significant source of blue diamonds in the world.
Harry Winston
Harry Winston was an American jeweler. He donated the Hope Diamond to the Smithsonian Institution in 1958 after owning it for a decade. He also traded the Portuguese Diamond to the Smithsonian in 1963.
Alrosa
Alrosa is a Russian group of diamond mining companies that specialize in exploration, mining, manufacture, and sale of diamonds. The company leads the world in diamond mining by volume. Mining takes place in Western Yakutia, the Arkhangelsk region, and Africa. Alrosa is Russia's leading diamond company accounting for 95% of country's diamond production and 27% of the global diamond extraction.
Letseng diamond mine
The Letšeng diamond mine, found in the landlocked Southern African kingdom of Lesotho, is owned by Gem Diamonds, Ltd. and the government of Lesotho, and at an elevation of 3,100 m (10,000 ft) it is the world's highest diamond mine.
Diamond (gemstone)
A diamond is one of the best-known and most sought-after gemstones. Diamonds have been used as decorative items since ancient times; some of the earliest references can be traced to 25,000 - 30,000 B.C.
Petra Diamonds
Petra Diamonds Ltd is a diamond mining group headquartered in Jersey. It has a diversified portfolio, with interests in eight producing mines in South Africa and Tanzania and an exploration programme in Botswana. Petra Diamonds' focus has shifted from exploration to production, becoming one of the largest independent producers of diamonds in Africa. In June 2012, Petra owns 5 of the world's most productive mines historically. These mines include the Cullinan Diamond Mine famed for having produced the world's largest rough and polished diamond. It is listed on the London Stock Exchange.
Star of Sierra Leone
The 968.9-carat (193.78 g) Star of Sierra Leone diamond was discovered by miners on February 14, 1972, in the Diminco alluvial mines in the Koidu area of Sierra Leone. It ranks as the fourth-largest gem-quality diamond and the largest alluvial diamond ever discovered.
Brown diamonds
Brown diamonds are the most common color variety of natural diamonds. In most mines, brown diamonds account for 15% of production. The brown color makes them less attractive as gemstones because of the reduced glimmer, and most are used for industrial purposes. However, improved marketing programs, especially in Australia and the United States, have resulted in brown diamonds becoming valued as gemstones and even referred to as chocolate diamonds.
Lucara Diamond
Lucara Diamond Corp. is a diamond exploration and mining company, operating in southern Africa but established in Canada. In November 2015, Lesedi La Rona, the world's second largest gem-quality diamond ever found, was found at the Karowe mine in Botswana.
Lesedi La Rona
Lesedi La Rona, formerly known in media as Karowe AK6 or as Quad 1 by the personnel at the mine, is the third-largest diamond ever found, and the second-largest of gem quality. Only the non-gem black Sergio and the gem-quality Cullinan were larger. It was found in the Karowe mine, in Botswana on 16 November 2015.
Golconda Diamonds
The 'Golconda Diamonds' are Indian diamonds mined in a specific geographic area within the historic Golconda Sultanate. Diamonds from these mines were transported to the city of Hyderabad to be cut, polished, evaluated and sold. Golconda established itself as a diamond trading center and, until the end of the 19th century, the Golconda market was the primary source of the finest and largest diamonds in the world. Thus, the legendary name 'Golconda Diamond' became synonymous with Golconda itself.