Presentation on theme: "Diamonds ADÁMAS. What are diamonds The word Diamond comes from the Greek word Adamas, which means indestructible. It is the only gem known to man that."— Presentation transcript:
What are diamonds 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 crystallized in a cubic arrangement. Diamonds have a range of unique properties: Diamond is the hardest known natural material on Earth. Diamond conducts heat 5 times faster than copper, which is why it feels cold to the touch. Pure diamond is the most transparent material known. It reflects visible light, ultra-violet light, and infrared light, and all the frequencies in between. Diamond can be an insulator or a conductor, so it can either allow electricity to pass through or block it. Diamond can survive intact in environments that will destroy other materials. It can survive severe physical, chemical and radioactive forces. If you place diamonds inside the human body they will not trigger an immune response.
Structure of diamonds Diamonds mined from the earth look like tumbled gems or beach glass. To turn the diamond into a beautiful gem, the diamond is cut with precise facets, or tiny polished faces. There are 58 total facets on the round brilliant diamond: 33 facets are in the crown and table located above the girdle, 24 facets in the pavilion and 1 facet at the bottom, or culet.
A well cut diamond will have an amazing brilliance and fire. This is caused by white light reflecting off the diamond’s surfaces and the mirrored depths of the pavilion. The key to desirable fire and brilliance is proportion. Light striking a shallow cut diamond will fall out the other side and not reflect back to the top. Light striking a deep cut diamond will get lost in the pavilion and also be unable to reflect back to the top.
While many diamonds appear colourless, or white, they may actually have subtle yellow or brown tones that can be detected when comparing diamonds side by side. Colourless diamonds are the rarest and most valuable of all. Colour variations are a result of the natural forces (i.e., temperature, pressure, trace elements) at work during the formation of diamonds within the Earth. Because subtle colour variations dramatically affect the value of a diamond, a colour grading scale is used to categorize the shading differences from one diamond to the next. Diamonds are graded according to the GIA (Gemological Institute of America) colour chart.
Colour GradeDescriptionAppearance DColorlessStone looks absolutely clear, with no hint of color to the eye in color grading or mounted E F GNear Colorless Some colour tint is visible during grading. Mounted in a setting, stone appears colourless. GHI colour diamonds are considered very nice diamonds for fine jewellery. H I J KFaint YellowYellow or greyish tint is obvious during colour grading. Mounted, this stone still shows a tint of colour L M N-ZLight YellowObvious yellow or greyish colour Z+FancyBright, remarkable colour - usually blue, pink, yellow
How are diamonds made There are 5 major steps involved in the manufacture of diamonds: Mining, Crushing, Separating, Greasing and Cutting. Mining: Block caving is the most commonly used method in excavating diamonds from kimberlite deposits. First, a large vertical hole is excavated. Levels are placed approximately every 40 feet (12 m). Along these levels are horizontal tunnels known as scraper drifts. In the drifts, there are small inclined cone shaped openings. When a horizontal slice is cut above the cones, the kimberlite begins to break off and fall into the cone and into the scraper drift. The material is then pushed onto trucks. The trucks travel underground through the mining area and take the collected kimberlite to a crushing device. Crushing: In the crushing operation, large chunks of kimberlite are broken up into more easily transportable segments. After an initial crushing, the kimberlite passes through a grizzly, or a set of iron bars. The crushed kimberlite is then taken above the surface for further processing. When no more kimberlite is found entering the cones, the area is depleted and work moves on to a lower level.
Separating: The actual diamonds must be separated from the rock that surrounds them. Crushing or milling the excavated material is the first step, but this is done in a rudimentary form so as not to damage the potential gems inside. Next, a gravity-based device is used to sort the diamond-containing portions— called the concentrate—from the tailings, or the filler rock. Commonly used methods to separate the two are media separators, hydrocyclone or washing pan. Greasing: After this rudimentary separation, the concentrate moves to a greasing area. Mixed with water, the kimberlite and diamond mixture is placed on a greased belt or table. This device is usually slanted and vibrated. The method operates on the premise that diamonds newly excavated will not become wet when brought into contact with water. Instead they will stick to the grease. The water then carries away the remaining non-diamond particles. The diamond-laden concentrate is then swept off the table and boiled to remove the traces of grease. Cutting: In cutting, a minuscule groove is incised into the surface of the diamond, and a cleaving iron is inserted into the groove. With a quick, forceful blow, the diamond should split perfectly along its naturally occurring planes. The lapidary determines further cuts by marking them off on the surface with ink. Next, a diamond saw, oiled with the unusual combination of diamond dust and olive oil, is rotated vertically on the surface of the raw gem. This device divides the diamond into new segments.
Where are diamonds produced Diamonds were first discovered in India around 800 B.C. The main historical diamond fields were found in the states of Andhra Pradesh, Chhattisgarh, Madhya Pradesh and Orissa. At that time, the only other known source of diamonds was Borneo. Until the discovery of the Brazilian deposits in 1775, the world's supply came almost entirely from India. When most of the diamond sources in India were depleted, Brazil subsequently became the next diamond centre of the world. Today, almost 80% of the world's diamonds are cut and polished in India, but the country accounts for a very small percentage of overall diamond production. Before the 1870s, diamonds were still rare and were associated only with nobility. In 1866, the first diamond was discovered in South Africa. This rich deposit transformed the diamond from a rare gem into a precious stone which is now available to anyone who can afford it. The Congo, Ghana, Namibia and Angola soon became other major suppliers. Below: A diamond mine
RankCountry% of production worldwide 1Russia22.40 2Botswana19.90 3Congo18.60 4Australia13.20 5South Africa9.10 6Canada8.10 7Angola4.80 8Namibia1.30 9Ghana0.60 10Brazil0.40 Other1.50
Types of diamonds When we talk about " diamond types" we are not talking about folks who really like diamonds. Actually, it's pretty scientific -- a system of classifying diamonds according to trace elements in the crystal. The trace elements are trace impurities. The impurities that determine diamond type dwell deep in the lattice of a diamond crystal. These trace elements are figuratively invisible, millions of times smaller than the tiniest inclusion. But we do see their effect on a diamond's colour. The impurities affect colour through a mechanism of absorption. On the basis of chemical properties, diamonds are classified into Type 1 and type 2. On the basis of clarity, diamonds are graded into several types by the The U.S. Federal Trade Commission
Type 1Type 2 Type 1 diamonds are most common. Nitrogen is the impurity. Type 1 diamonds are further categorized as Type Ia & Type Ib. Formed under extremely high pressure and temperature, these diamonds have no impurities. Besides being colourless, Type 2's tend to form large and irregular crystals. Type 1a - estimated that 98% of all natural diamonds are Type 1a with nitrogen concentrations up to 0.3%. Type 1a diamonds have another sub-classification. Type 1aA - The nitrogen atoms are in pars and don't effect the diamond's colour Type 1aB - Nitrogen atoms form in large even-numbered clusters and result in yellow / brown. Type 2a - these are probably the best of the best, 2% of all natural gem diamonds. Australian diamonds tend toward Type 2a. Example are the Cullinan and the Koh-i-noor Type 1b diamonds are much more rare. Only about 0.1% of natural diamonds are Type 1b. The nitrogen in these crystals is only 0.05% and is widely distributed. As a result, the crystal absorbs the green spectrum. That means the diamonds tend toward more vivid colours of yellow and brown. Type 2b - Even rarer than Type 2a at 0.1% of all natural diamonds, Type 2b diamonds have insignificant nitrogen impurities. What sets them apart is boron. Boron impurities tend to produce diamonds with a blue or grey tint.
Clarity is an indication of a diamond's purity. Clarity is determined by a diamond's naturally occurring internal characteristics. These characteristics are sometimes not visible to the naked eye and they are what make each diamond unique. The characteristics, or inclusions, may look like crystals, feathers, clouds or dark spots and the quantity, size, and location of these inclusions does have an affect on a diamond's value.
Where are diamonds used One of the most common uses of diamonds is in jewellery. Well cut diamonds are very expensive because they make excellent jewellery. Synthetic diamonds (man-made) are mainly used for industrial applications. They are put in drill bits and saws to cut different materials. Other gemstones can be cut and polished by diamonds. Precision cutting can be achieved by using diamonds. This is called fine engraving. Windows that cover the openings of lasers, x-rays and vacuum chambers have diamonds in them. Diamonds are used as micro-bearings in many small mechanical devices. The main use is in watches. Diamonds are capable of absorbing a lot of heat. That makes them ideal for use in microelectronics to conduct heat away from heat-sensitive parts of the electronics. Microchips and computer processors are often coated in diamonds as they are semiconductors of electricity.
Thank you Project submitted to: Mrs. Manju Somani Mrs. Litha Leela Krishnan Mrs. Shikha Biswas Group Members: 35)Urvi Karnatak- What are diamonds 12)Jay Mehta- Structure of diamonds 23)Purav Jhaveri- How are diamonds produced 24)Ravi Shah- Where are diamonds produced and PPT 11)Himanshu Mittal- Types of diamonds 36)Yashraj Singh Parmar- Uses of diamonds