Diamond

Diamond. The name diamond derives from the ancient Greek ἀδάμας (adámas), “own”, “unalterable”, “unbreakable, indomitable”, “I rule, I dome” However, it is thought that diamonds were first recognized and mined in the India , where significant alluvial deposits of this stone could have been found many centuries ago along the Penner , Krishna and Godavari rivers .

Summary

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  • 1 Story
  • 2 Natural history
  • 3 Use
  • 4 Material properties
  • 5 Hardness
  • 6 Industrial use
  • 7 Electrical conductivity
  • 8 Tenacity
  • 9 Color
  • 10 Identification
  • 11 world famous diamonds
  • 12 Sources

History

It is considered proven that diamonds have been known in India for at least 3,000 years, and it is conjectured that they were known 6,000 years ago. Diamonds have been treasured as gems since their use as religious icons in ancient India. Its use in engraving tools also dates back to earlier human history. The popularity of diamonds has been growing since the 19th century due to their increasing supply, better cutting and polishing techniques, growth in the world economy, and innovative and successful advertising campaigns. In 1813 , Humphry DavyHe used a lens to concentrate the sun’s rays on a diamond in an oxygen atmosphere, and showed that the only product of combustion was graphite . carbon dioxide , proving that the diamond was made of carbon. Subsequently, it demonstrated that, in an oxygen- depleted atmosphere , diamond becomes

Natural History

Natural diamond formation requires very specific conditions — exposing carbon-containing materials to high pressure, ranging from 45 to 60 kilobars, but at a comparatively low temperature range of approximately 900-1,300 ° C. These conditions are found in two places on Earth; in the mantle of the lithosphere under relatively stable continental plates, and at the meteorite impact site.

Use

The most familiar today is as gems used for decoration, a use that dates back to ancient times.

Material properties

Diamond is an allotrope of carbon . A diamond is a transparent crystal of tetraedrally bonded carbon atoms (sp3) that crystallizes in the diamond lattice, which is a variation of the face-centered cubic structure. Diamonds have been adapted for many uses, due to the exceptional physical characteristics. The most notable are its extreme hardness and thermal conductivity (900–2,320 W / (m • K))], as well as the wide band gap and high optical dispersion. Above 1,700 ° C (1,973 K / 3,583 ° F) in a vacuum or in an oxygen-free atmosphere, diamond is converted to graphite; in air the transformation begins at approximately 700 ° C. Naturally occurring diamonds have a density ranging from 3.15–3.53 g / cm3.

Hardness

Diamond is the hardest natural material known so far, where hardness is defined as scratch resistance. It has a hardness of 10 (maximum hardness) on the Mohs scale of mineral hardness. Its hardness has been known since ancient times, and is the source of its name. The hardest natural diamonds in the world are from the Copeton and Bingara fields, located in the New England area in New South Wales. The hardness of diamonds contributes to its suitability as a gem. Because they can only be scratched by other diamonds, they keep their polishing extremely well. Unlike other gems, they are well suited to everyday use due to their scratch resistance perhaps this contributes to their popularity as the gem of choice in engagement rings and wedding rings, which are often worn every day for decades.

Industrial use

It has been historically associated with its toughness; This property makes diamond the ideal material for cutting and polishing tools. As the hardest known natural material, diamond can be used to polish, cut, or erode any material, including other diamonds. Common industrial adaptations of this skill include drill bits and saws, and the use of diamond powder as an abrasive. The less expensive industrial grade diamonds, known as bort, with many flaws and poorer color than gems, are used for such purposes. It is not suitable for high-speed ferrous alloy machinery, since carbon is soluble in iron at the high temperatures created by high-speed machinery,

Electric conductivity

Other specialized applications also exist or are being developed, including their use as semiconductors: some blue diamonds are natural semiconductors, in contrast to most other diamonds, which are excellent electrical insulators. The conductivity and blue color originate from the boron impurity. Boron replaces carbon atoms in the diamond network, giving a gap in the valence band. A substantial conductivity is commonly observed in nominally undoped diamonds, which have grown by chemical vapor deposition. This conductivity is associated with species related to surface adsorbed hydrogen, and can be removed by annealing or other surface treatments.

Tenacity

Toughness refers to the ability of the material to resist breaking due to a strong impact. The tenacity of natural diamond has been measured as 2.0 MPa • m1 / 2, and the critical stress intensity factor is 3.4 MN • m − 3/2. These values ​​are high compared to other gems, but low compared to most engineering materials. As with any material, the microscopic geometry of a diamond contributes to its resistance to fracture. Diamond has a fracture plane and hence is more brittle in some orientations than others. Diamond cutters use this attribute to break some stones, as a previous step to faceting.

Colour

Brown colored diamonds at the Smithsonian National Museum of Natural History. The origin of the colors in the diamond is in the defects of networkand impurities. Most diamond impurities consist of the replacement of a carbon atom in the crystal lattice. The most common impurity, nitrogen, causes a light to intense yellow coloration, depending on the type and concentration of nitrogen present. The Gemological Institute of America (GIA) classifies low yellow and brown saturation as diamonds in the normal color range, and applies a grading scale from ‘D’ (colorless) to ‘Z’ (slightly yellow). Nitrogen is by far the most common impurity found in diamond gems, and is responsible for the yellow and brown in diamonds. Boron is responsible for the grayish blue color. Different colored diamonds, like blue, are called “fancy colored” diamonds, and fall under a different grading scale. Color in diamonds has two additional sources: irradiation (usually by alpha particles), which causes color in green diamonds; and physical deformations of the diamond crystal known as plastic deformations. Plastic deformation is the cause of color in certain brown diamonds and perhaps some pink and red. In order of rarity, colorless diamonds, by far the most common, are followed by yellows and browns, then blues, greens, blacks, translucent whites, pinks, violets, oranges, purples, and the rarer, red. “Black” diamonds are diamonds that are not truly black, but contain numerous dark inclusions that give the gem its dark appearance. which causes color in green diamonds; and physical deformations of the diamond crystal known as plastic deformations. Plastic deformation is the cause of color in certain brown diamonds and perhaps some pink and red. In order of rarity, colorless diamonds, by far the most common, are followed by yellows and browns, then blues, greens, blacks, translucent whites, pinks, violets, oranges, purples, and the rarer, red. “Black” diamonds are diamonds that are not truly black, but contain numerous dark inclusions that give the gem its dark appearance. which causes color in green diamonds; and physical deformations of the diamond crystal known as plastic deformations. Plastic deformation is the cause of color in certain brown diamonds and perhaps some pink and red. In order of rarity, colorless diamonds, by far the most common, are followed by yellows and browns, then blues, greens, blacks, translucent whites, pinks, violets, oranges, purples, and the rarer, red. “Black” diamonds are diamonds that are not truly black, but contain numerous dark inclusions that give the gem its dark appearance. Plastic deformation is the cause of color in certain brown diamonds and perhaps some pink and red. In order of rarity, colorless diamonds, by far the most common, are followed by yellows and browns, then blues, greens, blacks, translucent whites, pinks, violets, oranges, purples, and the rarer, red. “Black” diamonds are diamonds that are not truly black, but contain numerous dark inclusions that give the gem its dark appearance. Plastic deformation is the cause of color in certain brown diamonds and perhaps some pink and red. In order of rarity, colorless diamonds, by far the most common, are followed by yellows and browns, then blues, greens, blacks, translucent whites, pinks, violets, oranges, purples, and the rarer, red. “Black” diamonds are diamonds that are not truly black, but contain numerous dark inclusions that give the gem its dark appearance.

ID

There are physical methods for identifying diamonds, such as the use of heavy liquids; It is about, using the density of the diamond as a criterion, immersing the sample in a solution of methylene iodide, in which the gem will float or sink if it is a diamond or not. A few years ago, devices were made that use the thermal conductivity of diamond to distinguish it from other transparent gems. At first they were very useful, especially for those who did not have gemological knowledge, since simply by touching the gem with these devices you could determine if that gem was diamond or not. But with the appearance of moissanite, another new imitation of diamond, which has a thermal conductivity very similar to that of diamond, the reliability of these devices was questioned. There are also direct observation methods to identify a diamond. Gemological microscopes allow the internal inclusions of the gem under study to be observed, and an expert can determine which inclusions are characteristic of a diamond and which are not. Transparency is another characteristic of diamond, being less transparent than some of its imitations.

World famous diamonds

Kohinoor . Beautiful gem that weighed in roughly 186 carats. Its name means mountain of light, it was Nadir, Sha of Persia , who named it that way in the year 1739 . Later it belonged to Queen Victoria , after carving, it was part of the crown of Queen Mary and is currently found in the crown of Elizabeth II .

Jubilee . He was presented to Queen Victoria on the occasion of the celebration of his 16 years of reign. Raw it weighed 650.80 carats, after carving it weighed 245.35 carats. It is currently on display in the De Beers Pavilion in Johannesburg .

Hope Blue Diamond . It was part of a Buddha statue, from where it was stolen and sold to the Greater Mongol. Later it belonged to Louis XIV , from which it was stolen during the French Revolution . At the beginning of the 19th century, the banker Henry Hope acquired it and gave it its name. This diamond passed through the hands of numerous people, most of whom ended in ruin, leading to the legend that those who possessed it would be persecuted by the curse of the Hope. It weighs 42.52 carats and is currently housed in the Smithsonian Institution’s Museum of Natural History in Washington .

Florentine or Tuscan . Its origin is unknown, it is known that in 1697 this diamond became part of the Medici , a family of Italian merchants and bankers. Later it was used as a brooch by the Royal House of Hagsburg . At present it is unknown where it is. Its weight is 137.27 carats.

Tiffany . It was discovered in the Kimberley mine , South Africa , in 1878 . Acquired by famous Tiffany jewelry in New York , it weighs 128.58 carats. Today it is part of the jewel known as “Bird on rock”, which has only been used twice once by actress Audrey Hepburn , to promote the movie “Breakfast with diamonds”.

Great Mughal . One of the most famous diamonds of all time, second only to size by the Cullinan and shaped like a cross-sectioned egg. The original rough stone came from India , and in the hands of a rather clumsy cutter it was transformed into a 280-carat cut diamond. Today it belongs to the Shah of Persia.

Cullinan . Famous diamond found in South Africa. Named after the owner of the mine where it was found, Sir Thomas Cullinan, this rough gem weighed 3,196 carats. As a birthday gift, it passed into the hands of Edward VII of England . From the Cullinan 9 great gems and 96 smaller pieces were extracted: the nine largest became part of the history of jewelry as the Nine Stars of Africa , and currently belong to the English royal family, or to the Crown treasure

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