Published on November 14, 2007
Diamondat a glance: Diamond at a glance What Is A Diamond? : What Is A Diamond? The word Diamond comes from the Greek word Adamas, which means indestructible. It is the only gem known to man that is made of a single element, Carbon, besides graphite. Diamond is completely made of Carbon atoms (Chemical Composition - C) crystallized in a cubic (isometric) arrangement HISTORY OF DIAMONDS : HISTORY OF DIAMONDS From myths about valleys of diamonds protected by snakes, to the production of millions of carats in rough diamonds each year, the history of diamonds is one of mystical power, beauty and commercial expertise. Early History : Early History The first recorded history of the diamond dates back some 3,000 years to India, where it is likely that diamonds were first valued for their ability to refract light. In those days, the diamond was used in two ways-for decorative purposes, and as a talisman to ward off evil or provide protection in battle The Middle Ages : The Middle Ages During the Middle Ages more attention was paid to the worth of diamonds, rather than the mystical powers surrounding them. Due to the heightened public awareness of the value of diamonds, mine owners perpetuated myths that diamonds were poisonous. This was to prevent the mineworkers swallowing the diamonds in an attempt to smuggle them out of the mines. Recent Times : Recent Times During the mid-nineteenth century, diamonds were also being discovered in eastern Australia. However, it was not until late 1970's, after seven years of earnest searching, that Australia's alleged potential as a diamond producer was validated. On October 2nd 1979, geologists found the Argyle pipe near Lake Argyle: the richest diamond deposit in the world. Since then, Argyle has become the world's largest volume producer of diamonds, and alone is responsible for producing over a third of the world's diamonds every year Diamonds found in meteorites : Diamonds found in meteorites Diamonds in meteorites were discovered in Arizona or South Pole and they contained minuscule crystals of diamonds. In 2004, The Harvard-Smithsonian Center for Astrophysics has announced the discovery of a mass of crystallized carbon formerly known as star BPM 37093, now known as the biggest diamond in the galaxy, fifty light years away from Earth in the constellation Centaurus. The diamond is estimated to be 2,500 miles across and weighs approximately 10 billion-trillion-trillion carats – a one, followed by 34 zeros = 10,000,000,000,000,000,000,000,000,000,000,000 carats. For more informations, click: 10 Billion-Trillion-Trillion-Carat Diamond Found in Space THE MOST FAMOUS DIAMONDS: THE MOST FAMOUS DIAMONDS Golden Jubilee : Golden Jubilee Cut: Rose-cushion Color: Fancy Yellow Brown Polished weight:545.67 carats Rough weight:755.00 carats Information: The Golden Jubilee is the largest cut diamond of the world, it has 15.47 carats more than the cullinan I. It is mounted on the imperial crown of Thailand. The Cullinan: The Cullinan The Cullinan is the one of largest diamond ever discovered. It was found in a mine near Pretoria, South Africa, and weighed 3,106 carat. It was named after the discoverer of the mine. It was so incredibly valuable, that the owner came up with the idea of organising a heavily secured convoy transporting a fake stone, while sending the real stone by ordinary post. Once in London, the king had the huge stone divided into 106 smaller diamonds. The biggest stone, the pear-shaped Cullinan I, still weighed 530 carat. This stone and the smaller parts of the original diamond are part of the British crown jewels Iranian Diamonds Collection: n°23 : Iranian Diamonds Collection: n°23 Cut:Multi Faceted Trapezoid Color:Colorless Polished weight:38.18 carats Information:These African diamonds were acquired by Nasseridin Shah on his third trip to Europe in 1889, and are collectively known as the Iranian Yellows. The largest diamond in this collection, which is a 152.16 carats stone, is not pictured here and smallest is a 38.18 carats. They are on display in the Iranian Treasury. Slide12: Darya-i-Nur Cut:Rectangular Color:Light Pink Polished weight:186.00 carats Information:This stone measuring 41.40 × 29.50 × 12.15mm. The name means Sea of Light, River of Light, or Ocean of Light. The stone is estimated to weigh somewhere between 175 and 195 carats, and it is a light pink color. The reason the exact weight is not known is because the stone cannot be removed from its setting without major risk of destroying the setting. It is more than likely that the stone was cut from the Great Table Diamond, and stone that was described by Jean Baptiste Tavernier as being over 400 carats, pink, and very flat. Slide13: The Koh-I-Noor or Mountain of Light The Koh-I-Noor or Mountain of Light is the oldest of all famous diamonds. It was found along the shores of the river Ganges in India 700 years ago. At the time, its value was estimated to be the equivalent of a day’s pay of the entire population of the world. A series of wars and conquests lead the Koh-I-Noor to the national treasuries of Pakistan, Persia and India. After 500 years of bloodshed, the Mountain of Light ended up in the treasury of Queen Victoria. She had the stone cut to an oval of 138.93 carat. Today, it is still part of the British crown jewels The Star of South Africa : The Star of South Africa The Star of South Africa is famous for the consequences of its discovery. It starts with a Hottentot herder, who found a ‘shiny pebble’ and gave it to his neighbour, Shalk van Niekerk. To have it examined, the latter entrusted the stone to a commercial traveller, who instead shamelessly sold the diamond to reap the profit for himself. Van Niekerk, who had learnt his lesson, was convinced that there were more precious stones to be found in his region. His search proved him right. He discovered the Star of South Africa at the house of a shepherd, whom he gave everything he possessed: 500 sheep, 10 oxen and a horse. This would turn out to be a good exchange, for he sold the diamond for 56,000 dollars. The stone was cut as a brilliant and weighs 47.75 carat. The story of the discovery and sale of the stone spread like wildfire and triggered off the diamond rush in South Africa. Diamond Crystals : Diamond Crystals The diamond octahedron has the shape that we describe as a diamond. While it is the most common shape for a diamond crystal, cubes, dodecahedra, and combinations of these three shapes are common. All are highly symmetrical, with equal dimensions in three perpendicular directions, and all are manifestations of the cubic crystal system to which the mineral diamond belongs Hardness: Hardness Diamond is renowned for its hardness. Hardness is the measure of a substance's resistance to being scratched, and only a diamond can scratch another diamond. Diamond is the hardest substance known. Slide17: Diamond is the hardest natural substance on earth, but if placed in an oven at 1405 degrees Fahrenheit (763 degrees Celsius), it will vanish. Only a small amount of carbon dioxide will have been released. Formation in the earth : Formation in the earth Diamond is a polymorph form of carbon. The other form is graphite. For carbon to turn into diamond, 3 factors are needed: time, very high temperature (around 1,000 degrees) and very high pressure above 30 kilobars (kb). The Pressure and Temperature conditions within the earth, are known as geotherms. Any changes of « P » (Pressure) and « T » (Temperature) within the environment where diamonds are formed, may reverse the cycle back to graphite or gas. The main bearing diamond rocks are kimberlite (the name proposed by Lewis in 1888 is for the Kimberley district in South Africa), lamproite. Diamonds can be formed going down towards the mantle of the earth , going up towards the surface of the earth and also on impact . How and where are diamonds formed? : How and where are diamonds formed? Diamonds form between 120-200 kilometers or 75-120 miles below the earth's surface. According to geologists the first delivery of diamonds was somewhere around 2.5 billion years ago and the most recent was 45 million years ago. According to science, the carbon that makes diamonds comes from the melting of pre-existing rocks in the Earth's upper mantle. There is an abundance of carbon atoms in the mantle. Temperature changes in the upper mantle forces the carbon atoms to go deeper where it melts and finally becomes new rock, when the temperature reduces. If other conditions like pressure and chemistry are right then the carbon atoms in the melting crystal rock bond to build diamond crystals. There is no guarantee that these carbon atoms will turn into diamonds. If the temperature rises or the pressure drops then the diamond crystals may melt partially or totally dissolve. Even if they do form, it takes thousands of years for those diamonds to come anywhere near the surface. How do diamonds get to the surface?: How do diamonds get to the surface? Diamonds ascend to the Earth's surface in rare molten rock, or magma that originates at great depths. Carrying diamonds and other samples from Earth's mantle, this magma rises and erupts in small but violent volcanoes. Just beneath such volcanoes is a carrot-shaped "pipe" filled with volcanic rock, mantle fragments, and some embedded diamonds. The rock is called kimberlite after the city of Kimberley, South Africa, where the pipes were first discovered in the 1870s. Another rock that provides diamonds is lamproite. The volcano that carries diamond to the surface emanates from deep cracks and fissures called dikes. It develops its carrot shape near the surface, when gases separate from the magma, perhaps accompanied by the boiling of ground water, and a violent supersonic eruption follows. The volcanic cone formed above the kimberlite pipe is very small in comparison with volcanoes like Mount St. Helens, but the magma originates at depths at least 3 times as great. These deep roots enable kimberlite to tap the source of diamonds. Magmas are the elevators that bring diamonds to Earth's surface. How do diamonds get to the surface?: How do diamonds get to the surface? The search for diamonds has determined that most are derived from kimberlite pipes in the oldest, nuclear portions of the continents, where the basement rocks are older than 1.5 billion years. The oldest parts of continents are called cratons, and can be divided into two terranes: Archean-age archons, which are older than 2,500 million years, and Proterozoic-age protons, which are 1,600 -- 2,500 million years old. The distribution of these terranes is shown on the map. The complex volcanic magmas that solidify into kimberlite and lamproite are not the source of diamonds, only the elevators that bring them with other minerals and mantle rocks to Earth's surface. Although rising from much greater depths than other magmas, these pipes and volcanic cones are relatively small and rare, but they erupt in extraordinary supersonic explosions. Slide23: Kimberlite and lamproite are similar mixtures of rock material. Their important components include fragments of rock from Earth's mantle, large crystals, and the crystallized magma that glues the mixture together. The magmas are very rich in magnesium and volatile compounds such as water and carbon dioxide. As the volatiles dissolved in the magma change to gas near Earth's surface, explosive eruptions create the characteristic carrot- or bowl-shaped pipes. Slide24: Kimberlite magma rises through Earth's crust in networks of cracks or dikes. The pipes only form near Earth's surface. This cross-section of a kimberlite pipe shows the carrot-shaped profile produced by explosive eruption. The root zone starts in fissures, where gases are released from the rising magma and drive the eruption; they blow out the fragment-laden kimberlite to form the volcano's tuff ring and fill the pipe. Slide26: These drawings illustrate the formation and filling of the typical champagne-glass shape of a lamproite pipe. The initial stage of the eruption, powered by gases either from the lamproite magma or from boiling ground water, corrodes the hosting rock to form the champagne-glass shape (top). The eruption then produces particles of ash, lapilli, and pumice that partially fill the crater and form a tuff ring (middle). Finally, the crater fills with a lava pond from the degassed lamproite magma (bottom). Slide27: Today diamonds are mined in about 25 countries, on every continent but Europe and Antarctica. However, only a few diamond deposits were known until the 20th century, when scientific understanding and technology extended diamond exploration and mining around the globe. For 1,000 years, starting in roughly the 4th century BC, India was the only source of diamonds. In 1725, important sources were discovered in Brazil, and in the 1870s major finds in South Africa marked a dramatic increase in the diamond supply. Additional major producers now include several African countries, Siberian Russia, and Australia. It is a modern misconception that the world's diamonds come primarily from South Africa. However, diamonds are a world-wide resource. The common characteristic of primary diamond deposits is the ancient terrain that hosts the kimberlite and lamproite pipes that bring diamonds to Earth's surface. World wide diamondiferous deposits : World wide diamondiferous deposits World wide diamond mines : World wide diamond mines World wide diamonds producer : World wide diamonds producer Quality of diamonds (Classification of 19 producer countries ): Quality of diamonds (Classification of 19 producer countries ) Prospection: Prospection « South-African » method. With this method, which is very much used, we do not search the diamond itself, but heavy materials which accompany it and which are in greater numbers Littoral prospection The coastal prospection consists in searching the deposits which are at the edge of the littoral and on the beaches. The marine prospection is made by boats equipped with pumps in order to sample the diamantiferous gravel. Prospection related to hydrography : Prospection related to hydrography Alluvial prospection Contrary to the « South-African » method, the traditional alluvial prospection is characterized by the direct search of diamond in the alluvial gravels. The major disadvantage of this method is that it cannot be used in dry season, for a maximum of 5 months per year. Indeed, it is necessary to sample the rivers by digging small wells, which are very spaced at the beginning, then getting closer. Alluvial prospection in dense environment We could call this method the « Belgian method ». We search for diamonds directly. It is very much used in the Congo area, but the access to the deposits is made very difficult because of the dense forests and the absence of dry season. It is used in Zaire, in Central Africa and in Gabon. Diamond Deposits : Diamond Deposits Geologic processes create two basic types of diamond deposits, referred to as primary and secondary sources. Primary sources are the kimberlite and lamproite pipes that raise diamonds from Earth's mantle, where they originate. Secondary sources, created by erosion, include such deposits as surface scatterings around a pipe, concentrations in river channels, and fluxes from rivers moved by wave action along ocean coasts past and present. Mining of these deposits depends upon sufficient concentration and quality of diamonds. Mining : Mining Primary deposits The ground is blue in the volcanic cones. Two modes of mining exist: the open-cast (or open-pit) and the underground mine. Slide36: The open-cast mine This type of mining is very much used, especially in South Africa where there is the famous Kimberley mine called « Big Hole ». The mining is done by extracting the subsoil from the pipe using large hydraulic shovels. Hard rock is drilled and blasted with explosives so the broken material can be removed. The pipe is dug in tiers from which the materials to treat is put into trucks. Slide37: The underground mine can today reach depths of more than 1,000 meters. The content of diamonds is decreasing with the depth. Underground mining is more expensive than open-pit mining and requires more complex management and machinery. Two techniques of extractions are used: Mining: Mining Secondary deposits Eluvial & Alluvial Slide39: Eluvial deposit: the ground is yellow and near to the primary deposit. Alluvial deposit: this type of deposit is down in river beds over long distance. Marine littoral deposits : Marine littoral deposits For this type of mining powerful equipemnts and explosives are used to reach the diamantiferous gravel. The removal of the diamonds from the beaches requires the removal of a very large quantity of sand before being able to reach the diamantiferous gravel, and it is not rare to dig more than 20 meters below the sea level before reaching the diamantiferous gravels. There are enormous problems of water tightness. People work day and night. For the marine mining, the operations are rather delicate and require specific equipements. De Beers is the leader in this field and has boats and equipments unequalled, they have concessions in Angola, Namibia, etc... Ore processing : Ore processing Several techniques are used to process the diamantiferous ore. The techniques used will not be the same between artisanal and industrial mining, however there are some common elements: Crushing, not too fine (diamonds must not be crushed). Screening separates the sand from large elements. Washing disaggregates muds from ore. Concentrating process: rotary mixers, agitators, jigs, cyclones, cones, heavy-media separators (industrial mining only) are used to achieve density separations. Collecting diamond process is done using grease table or x-ray separators. Final separation and sorting is done visually. Slide42: Hymex: crushers Hymex: jigs Hymex: grease table Artisanal mining : Artisanal mining The material for this type of mining is very rudimentary: shovel, picks, sieves, pumps, etc... It is the will and the courage which is significant for the miner. It is the form of diamond mining which employs the most labor Semi-industrial mining : Semi-industrial mining Mobile diamond washing plant A mobile diamond washing plant can be a judicious choice, it is autonomous and it can be moved from a place to another. We recommend the French company Soditra-Sodiloc, for any mobile washing plant. Their website: Soditra-Sodiloc Dredge : Dredge Depending on the hardness of the bottom floor, it allows an average extraction of 7 to 10 cubic meters per hour. Industrial mining : Industrial mining The costs to be considered for this type of mining are considerably higher than the two other types of mining. Several parameters are essential: negotiations with the authorities, systematic study of the deposit (shape, dimensions, nature of the ground and the subsoil), study of the climatic conditions, provisioning of water and electricity, construction of roads, creation of schools and hospitals, etc... We can say to finish that it is the nature of the deposit which defines the mode of mining Certificate : Certificate Date of appearance Certificates appeared in 1970, they radically changed the ways and customs of the profession Its characteristics The certificate is a diamond grading report, describing objective factors, both qualitative and quantitative, and an almost infinite combination of all of the variables, based on the 4 c's (cut, clarity, color, and carat), measurements, and physical properties, define each stone: Its weight. Its clarity. Its color and fluorescence. Its proportions. Its finish. Its measurements: diameter, height or thickness, minimum and maximum diameter with the girdle. Slide49: Upon request, the diamond can be sealed in a plastic holder together with a microfilm of the certificate. Not only does the sealing keep the diamond safe from damage, grease and dirt, it is also a guarantee that a given certificate and the accompanying stone actually belong together. Slide50: Laser inscription of diamonds is a process of using a very fine, precise laser beam to write a customized personal message (« I love you », « Marry me », etc...) or certificate number on the girdle. The laser inscription is microscopic, totally invisible to the naked eye. It can only be seen with a jewelers' 10x magnifying loupe and it does not change the Color grade or clarity grade of a diamond Gemological laboratories : Gemological laboratories The main gemological laboratories in the world, and most known and rigorous are: IGI (International Gemological Institute) - Offices: Belgium, United States, India, Thailand, Japan. - Website: IGI GIA (Gemological Institute of America) - Offices: United States, Italy, Hong Kong, Japan, Korea, Thailand, Taiwan, United Kingdom, Russia, China. - Website: GIA HRD (Hoge Raad voor Diamant) - Office: Belgium. - Website: HRD AGS (American Gem Society) - Office: United States. - Website: AGS LFG (Laboratoire Français de Gemmologie) Service Public du Contrôle des diamants, perles fines et pierres précieuses in the Chambre de Commerce et d'Industrie of Paris. - Office: France. - Website: LFG Gubelin Gem Lab - Office: Switzerland. - Website: Gubelin Gem Lab About IGI : About IGI Established in Antwerp, New York, Mumbai, Bangkok, Tokyo, Toronto, Los Angeles, Dubai, Cavalese and Seoul, IGI is the world's largest independent gem certification and appraisal institute and is renowned for its quality services, extensive experience and know-how. IGI, the oldest institute of its kind in Antwerp, was founded in 1975 and along with its sister laboratory in New York, is one of the leading gemological institutions worldwide. Presently, a staff of just three has grown to over 350 professionals dedicated to a standard of excellence second to none. Today IGI issues more than 550,000 reports a year. About IGI : About IGI Ten years ago, only the diamond dealer was using gemological reports. Today, consumers have become more demanding and quality conscious about the products they buy. A jewelry buyer seeking an explanation of why two similar diamond rings are priced $1.000 apart is not satisfied with being told simply that one is a 'better' diamond. He or she will want to know why it's better. Consequently, today's jewelry consumers are more familiar with the 4C's than their parents were. Jewelers now consider supplying such information an integral part of any sale and modern retail training programs stress the importance of providing independent gemological reports for gems and jewelry in addition to educating the consumer. All this has led to an increase in demand for reliable grading or appraisal reports from credible organizations such as the International Gemological Institute (IGI). Thousands of jewelers, retail stores, insurance companies, internet sales organizations, catalogue companies (mail order), accounting and securities firms and consumers rely on IGI reports. Today the majority of good quality gem and jewelry items are sold with gemological reports Four C's : Four C's The Four C's: Cut, Color, Clarity and Carat weight are the different aspects of a diamond's characteristics and are considered the most important attributes to look for when choosing a diamond. Cut Carat Clarity Color The diamond industry uses these four main categories in order to set universal standards for evaluating a diamond's quality, value and beauty. Cut : Cut Diamond anatomy Polished diamond has 4 great parts: the table, the crown, the girdle and the pavilion Cut: Cut A round brilliant diamond has between 57 and 58 facets (depending on whether the culet was polished into a facet or closed to a point): Table: 1 facet. For the crown: 8 bezels, 8 stars and 16 upper girdle facets. For the pavilion: 8 pavilions and 16 lower girdle facets. Culet: 1 or 0 facet (if no culet facet). Also, in higher quality goods the girdle is frequently faceted, but these facets are not counted in the total. Shape and cutThe principal shapes of diamond : Shape and cut The principal shapes of diamond Cut Proportions : Cut Proportions Proportion scope: The tool used to measure the proportions of a diamond is a proportion scope It is necessary to consider all the proportions and not only some of them. An angle of crown too large or too small is indicated in remark. An open culet indicates a poor stone (except in the case of the old cuts). In melee, thick roundest indicate not very interesting stones. Cut Proportions: Cut Proportions Brilliance of a diamond following the proportions of its cut: Ideal cut: light is correctly reflected. Diamond has a beautiful brilliance and « fire ». Too shallow: light is lost out the sides causing the diamond to lose brilliance. Too deep: light escapes out the bottom causing the diamond to appear dark and dull. CutFinish : Cut Finish Symmetry The estimate of « symmetry » results from the observation from: The good alignment of the facets. The symmetry of the facets. The centering of the culet. The centering of the table. A diamond can have good symmetry and poor proportions. Some examples of symmetry defects: : Some examples of symmetry defects: CutPolish : Cut Polish The estimate of the « polish » results from the observation from: The presence of more or less polish lines. The presence of stripes. If the stripes are too numerous, they are mentioned in remarks. The estimate of symmetry and polished results in: Excellent Very good Good Fair Poor Carat: Carat The measuring unit is the metric carat, which corresponds to the fifth of 1 gram, that is to say 2 decigrams. Thus 1 carat = 0.2 gram. Color: Color Fancy Color diamond : Fancy Color diamond A diamond of really tint is a « diamond of particular Color »: fancy Color. The limit between a tinted stone (Z) and a stone of particular Color can be evaluated using a master Color grading set. There are diamonds of all the Colors: yellow, pink, blue, red, orange, green, black, cognac, champagne, etc... Certain Colors are very rare or exceptional, for example: red, green, certain intensities of blue or pink. In 1987, a Fancy Purplish-Red, 0.95 carat, round brilliant, was sold for US$ 926,315/carat, US$ 880,000 for the stone. Clarity : Clarity Observation of inclusions An inclusion is observed by the table and the pavilion to determine: Its size. Its contrast. Its position Clarity scale : Clarity scale Gem quality diamond : Gem quality diamond It is this type of quality which will be used in the jewelry industry. It must be of good Color and of good clarity, its shape is not very important because the diamond must be cut. This category of diamond requires a classification of the stones by subcategories: Industrial quality diamond : Industrial quality diamond As its name indicates, it is the quality of diamond which is reserved for industry. Industrial diamonds must nevertheless be of a good quality. The yellow color is preferred because of a greater hardness. One classifies them according to the weight, lower than 3 carats, but also according to their number of point. One uses them for example for the manufacture of dies, the tools for drilling, etc... Crushing-boart or boart : Crushing-boart or boart It is the worst diamond quality which exists, it is generally crushed and will be used as diamond dust which is used during the diamond polishing. De beers Group: De beers Group DIAMOND GEOLOGY : DIAMOND GEOLOGY Approximately 5,000 kimberlites are currently known in the world, but only 100 or so of these contain sufficient diamonds to be of economic interest. In most of those deposits that are of interest, diamond is present in concentrations of less than about one part in five million. De beers Group: De beers Group Today, the De Beers Group is the largest diamond mining company worldwide. With over 40% of global gem diamonds produced from our mines in South Africa, and in partnership with government in Botswana, Namibia and Tanzania, etc…. De beers Group: De beers Group De Beers is active in every category of diamond mining: Open pit Underground Alluvial Coastal Marine DE BEERS WORLD WIDE : DE BEERS WORLD WIDE Slide81: De Beers For more than a century, the name De Beers has been synonymous with diamonds. The company leads the world in diamond exploration, mining, recovery, sorting, valuation and marketing.