What is a Diamond? A diamond is a crystal completely made of the element carbon, except for trace impurities such as boron and nitrogen. The arrangement of the carbon atoms or its crystal structure within the diamond gives it its unique properties. As well as being the hardest known material, it is also the least compressible, the stiffest material and the best thermal conductor with an extremely low thermal expansion ( the tendency of matter to change in shape, area and volume in response to a change in temperature). Chemically inert to most acids and alkalis and immensely strong with a rigid structure and a very high melting point (3800°C). Diamond is the hardest known natural substance.
How are Diamonds formed? Diamonds are not created from the compressed trees and vegetation that produce coal as popularly thought. Experiments and the high density of diamonds show they can only form while under tremendous heat and pressure. The only places where these types of conditions exist are deep beneath the Earth's surface, about 150km to200km (90 to 120 miles) in a region beneath the crust known as the mantle where there is an abundance of carbon atoms. The pressure here combined with temperatures ranging from 900 to 1300 on the Celsius scale forced the carbon atoms together to crystallise in a cubic (isometric) arrangement creating diamonds.
How did they get nearer the surface? The diamonds and other substances from Earth's mantle are transported in magma that rises in a carrot-shaped "pipe" and erupts in small but violent volcanoes. The pipe is composed of a volcanic rock called kimberlite named after the city of Kimberley, South Africa, where the pipes were first discovered in the 1870s. Another rock that provides diamonds is lamproite. Geologists look for certain "indicator" minerals among the gravel of regions they think may host diamond-bearing pipes. Only 1% of Kimberlite pipes host economic diamonds. Shown in image the open pit of the Udachnaya Diamond Mine, Russia.
When were Diamonds formed? Recently, scientists studying diamonds have found the ages of thousands of diamonds from Southern Africa, where many diamonds are found. They discovered that there were only three times during Earths history when diamonds were made and that Earth no longer makes diamonds like it used to. The oldest diamonds were made 3.3 billion years the second time diamonds were made was 2.9 billion years ago. The youngest diamonds on Earth are 1.2 billion years old.
Are there other sources of diamonds? Alluvial diamonds is the term used to describe diamonds that have been removed from the primary source (Kimberlite) by natural erosive action over millions of years and eventually deposited in a new environment such as a river bed, an ocean floor or a shoreline. Around 10% of the worlds rough diamonds are sourced through industrial alluvial mining and 14% through small-scale informal alluvial diamond digging.
Other sources of diamonds include black diamonds called carbonado diamond, meaning burned or carbonised in Portuguese.
These are found in South America and Africa where they were deposited via an asteroid impact (not formed from the impact) about 3 billion years ago. These diamonds were formed by carbon-rich cosmic dust in an environment near carbon stars. The diamonds were incorporated into solid bodies that subsequently fell to Earth as meteorites.
How are fancy coloured diamonds created? The physical conditions necessary to colour a diamond naturally occur very seldom, for every natural colour diamond, there are 10,000 colourless ones. The formation of natural colour diamonds is a process that requires the presence of additional trace elements and distortions to the typical diamond crystal (called plastic deformation). During the creation of a diamond, if an element, e.g. boron, nitrogen interacts with its carbon atoms, the colour can change. Natural radiation and pressure on a diamonds structure can also intensify its colour.
Where are diamonds found? Diamonds are a world-wide resource.
Mined inAngola, Botswana, South Africa, Congo, Zimbabwe, Tanzania, Canada, United States of America,
Russia, India and Australia. 80% of of the worlds production comes from Africa and Russia.
The principle methods of diamond mining are:
Open-Pit diamond mining (or "Open-Cast Mining") is used when deposits of minerals are found near the surface as with kimberlite pipes. Open pit mining is used when the surface material covering the deposit is relatively thin and/or the minerals are imbedded in structurally unstable earth (cinder, sand or gravel) that is unsuitable for tunnelling.
Hard-Rock Mining refers to the techniques used to mine gems, minerals, and ore bodies by tunnelling underground and creating underground "rooms" or "stopes" supported by timber pillars of standing rock.
Placer Mining Placer Diamond Mining ("sand bank mining") is used for extracting diamonds and minerals from alluvial, eluvial, and or colluvial secondary deposits. Placer Mining is a form of open-pit or open-cast mining used to extract minerals from the surface of the earth without the use of tunnelling. Excavation is accomplished using water pressure (aka hydraulic mining), mechanized surface excavating equipment, or digging by hand (artisanal Mining).
Artisanal Mining or Small-scale mining This involves digging and sifting through mud or gravel river-bank alluvial deposits with bare hands, shovels, or large conical sieves. Labourers who work in artisanal diamond mining are called diamond diggers. Artisanal diamond mining is a form of "subsistence based" non-mechanised mining that is used in poorer countries throughout the world. It is used throughout West Africa, in conflict zones where mechanized mining is impractical and unsafe. Artisanal diamond mining accounts for 90% of Sierra Leone's diamond exports and is the country's second largest employer after subsistence farming. It is also used extensively in Angola, the Congo (DROC), and Liberia.
Panning for Diamonds
Once diamonds have been mined the diamonds must be sorted from other materials before the rough crystals are sorted and categorized according to their size, colour, shape and other characteristics. 80% of mined diamonds (equal to about 100 million carats or 20,000 kg annually) are unsuitable for use as gemstones and known as bort, are destined for industrial use. The dominant industrial use of diamond is in cutting, drilling, grinding, and polishing. Diamonds have a high density so an old but effective method used is a washing pan. Crushed ore is mixed with a muddy water suspension, called puddle, and all is stirred by angled rotating blades in the circular washing pan. The diamonds as they are heavier settle to the bottom. A grease table where wet gravel washes across 3 inclined surfaces covered with beeswax and paraffin. Diamonds stick to the grease while wetted waste minerals flow past. The surface of diamond is highly unusual in that it resists being wetted by water but sticks readily to grease.
A more high tech method is to use an x-ray separator. The x-ray separator system acts on a thin stream of particles from the concentrate accelerated off a moving belt into the air, where they encounter an intense beam of x-rays this makes the diamonds show fluorescence, this is multiplied by a photo multiplier activating a jet of air, deflecting the diamonds into a collector bin.
Final separation and sorting is done by eye separating diamonds into gem-quality, near gem-quality and industrial-grade diamonds. Diamonds are grouped into "sizes" - more than one carat; "smalls" - between 1 carat and 1/10th carat and "sand" - less than 1/10th carat, with some leeway for market pressures. Diamonds larger than about 15 carats are handled individually. Shape groups comprise "stones", "shapes", "cleavages", "macles" and "flats", describing characteristics familiar to the market.
The ultimate purpose of sorting is to estimate an asking price for the rough diamonds.
There are two aspects of moving diamonds from mine to dealer, the primary diamond marketing, which has been and still is largely controlled by De Beers Consolidated Mines, Ltd. through its majority control of the Central Selling Organization (CSO). While De Beers' market influence has decreased over the last few years, they still control the majority of the world's diamond production (an estimated 30% to 40%). The purchasing arm of the CSO not only buys diamonds from member mines around the world; it also finances mining technology for governments which do not have the means to mine their own deposits. Most of what is bought through the CSO is sent to London to be offered to buyers through De Beers marketing arm, the Diamond Trading Corporation (DTC).
The DTC holds sights ten week long selling sessions in a year. These sights are by invitation only, and only a handful of diamond manufacturers from around the world (called sight holder) are allowed to attend. These sight holders may cut the rough diamonds they buy themselves or they may sell some of the rough diamonds to smaller manufacturers. These smaller manufacturers cut the rough diamonds and sell the polished gems either to jewellery manufacturers or to diamond wholesalers.
Some independent miners elect not to sell their mine production to the De Beers cartel. Instead, they offer newly mined diamonds directly to other world buyers selling through closed bids and through private transactions. These buyers either cut and sell the diamonds themselves or sell them on to smaller manufacturers in the rough state. These smaller manufacturers cut the rough diamonds and sell the polished gems either to jewellery manufacturers or to diamond wholesalers.
What are Conflict Diamonds? (Blood Diamonds) These are diamonds that originate from areas controlled by forces or factions opposed to legitimate and internationally recognized governments, and are used to fund military action in opposition to those governments, or in contravention of the decisions of the Security Council. The General Assembly recognized that illegally traded conflict diamonds are a crucial factor in prolonging brutal wars particularly in central and western Africa and underscored that legitimate diamonds contribute to prosperity and development elsewhere on the continent. The tragic conflicts in Angola and Sierra Leone, fuelled by illicit diamond smuggling, have led to action by the Security Council. Under Chapter VII of the United Nations Charter, targeted sanctions have been applied against UNITA in Angola and the Sierra Leone rebels, including a ban on their main source of funding that is illicit diamonds. Diamond sanctions have also been applied against Liberia but are not yet in effect. Today, the flow of conflict diamonds has been reduced to considerably less than 1%.
The 5 operations necessary for the transformation of rough diamond into a cut diamond are as follows:
Cleaving - a sharp groove is carved into the diamond along the plane of weakness or cleavage, using another diamond or a laser. Then a steel blade is placed in the groove, and a sharp blow to the blade is applied splitting the stone.
Sawing - Sometimes, diamonds have to be cut against a cleavage plane, this cannot be done by cleaving. A rotating blade or laser is used to cut slowly through the diamond.
Bruting - The diamond is placed in a lathe, and another diamond in the lathe is rubbed against it to create the rough finish of the girdle. This procedure is performed only for diamonds that are to be finished as round, brilliant stones.
Cross Working - The crossworkers lay the foundation of the diamond following instructions to obtain the highest value for the finished product. Cross-workers make the decision whether to process a diamond, with the finished product containing inclusions or to produce a smaller diamond with fewer inclusions, and therefore a better quality. The work is done on a polishing disc driven by an electric motor. The disc is covered with diamond powder. The diamond to be polished is held in a clamp and 18 facets are polished one by one to very stringent measurements and angles.
Brillianteering - The function of brillianteers is to cut and polish extra 40 facets onto the already polished facets done by the cross-workers, in order to create a round brilliant cut diamond with 58 facets that will reveal the full brilliance and fire reflected by the polished diamond.
What is meant by Diamond Cut?
Crystals tend to cleave, or split, along lines called cleavage planes between layers of atoms. Due to its crystal structure, diamond has certain planes of weakness along which it can be split. Diamond is said to have perfect cleavage in four different directions, they cleave cleanly along planes parallel to the faces of an octahedron. This means it will separate neatly along these lines rather than in a jagged or irregular fashion. Diamond cutters take advantage of cleavage to cut diamonds efficiently. The term diamond cut does not refer to the shape of a diamond but the proportions of depth and width and the symmetry and uniformity of its facets. The proportions of width and depth have a large impact on diamond brilliance, the reflection of white light that we see when we look at a diamond. Ideally the diamond is cut so that when light enters the diamond crown it bounces off the pavilion on to the pavilion on the other side and is reflected out of the top the crown again showing brilliance and fire. Shallow cut diamonds loose light out of the bottom of the stone. The lack of light play makes shallow cut diamonds appear lifeless and glassy. Deep cut diamonds allow light to escape from the sides, darkening portions of the stone and loosing brilliance. Symmetry refers to the alignment of a diamond's facets, the flat and polished surfaces. The facets should be cut to achieve the best play of light called scintillation and it occurs when light bounces among the facets. Light doesn't reflect as it should if facets are misaligned.
Polish this refers to the quality of the finish given to the diamond. Tiny blemishes or scratches can lower a diamond polish grade.
Clarity is based on the fact that diamonds contain inclusions and the fewer inclusions the finer the clarity and the more valuable the stone.
There are basically two categories of inclusions found in natural diamonds. Syngenetic inclusions formed at the same time as the diamond and Epigenetic inclusions formed afterwards. The main types of inclusions are termed Crystal, Clouds, Feathers, Naturals.
Crystals - are minute crystals of other minerals such as garnet, diopside, spinel, olivine, calcite, iron oxides, silica or even other small diamonds that were absorbed by the diamond crystal as it was still growing.
Clouds - a grouping of a number of extremely tiny light crystals called pinpoints that are too small to be distinguishable from one another. The result is that this grouping often looks like a soft transparent cloud inside the diamond which can detract from a diamond's clarity.
Naturals - refers to the original surface of the rough diamond which has not been polished and left as it is. Naturals are usually left on or near the girdle of the diamond to retain as much of the original weight as possible. Indented naturals are also seen to exist on some stones, where the portion of the natural is seen to dip inside slightly from the diameter of the stone. Here the cutter usually leaves the indented natural either at the girdle or pavilion of the stone, in order to keep it less noticeable. Indents can be removed if the cutter polishes it out however, this would result in a drop of the weight of the diamond.
Feathers - are a separation within the diamond due to either cleavage or fracture which is often white and feathery in appearance. Small feathers do not usually affect a diamond's durability unless they penetrate the surface on the top of the stone. A feather that breaks through the surface in a vulnerable area increases the risk of breaking the stone.
Carbon Spots - are black spots inside a clear diamond. When a diamond is being formed it may not totally crystallize leading to the presence of small dots of black carbon. The effect on the clarity of the diamond depends on the size of the imperfection.
Laser lines - are not a natural inclusion. These vapour like trails are left behind when lasers are used to remove dark inclusions from the diamond. The machine-made trails look like tiny strands of thread that begin at the diamond's surface and stretch inward to the point where the inclusion was removed.
Carat is the weight of a diamond, carat is abbreviated as "ct.". Carat weight is also expressed as "points" to describe diamonds which weigh less than 1ct.
One carat diamond equals 0.2 grams and or 100 points.
1ct = 100 points
3/4 ct = 75 points
1/2 ct = 50 points
1/4 ct = 25 points
Therefore a .50 carat diamond can be called either 50 points or 1/2 of a carat.
Two diamonds of equal weight can be different value depending on their quality.
Colour- Diamonds are graded according to their inner body hue using a white to yellow scale, the whiter the diamond the higher the price.
Fancy Coloured Diamonds - unlike colourless and near-colourless diamonds which are valued for their lack of colour, fancies are valued for the intensity of their colour.
Colour Treatments - gemologists can influence the colour of a diamond through various processes. These processes can often increase the value of diamond that may not be as desirable in its original state. However all certificated diamonds should state whether or not the diamond in heat treated.
HPHT Treatment stands for high pressure, high temperature treatment. This process is often used to enhance the appearance of a diamond, many times changing its colour or making it colourless. This type of treatment is considered permanent, and this type of diamond should be less expensive. If a diamond has received a HPHT treatment, the jeweller should disclose this.
Irradiation/High Heat Treatment - Diamonds of Different Colours.
This process involves first exposing the diamond to radiation and then to high heat. Follow-up high heat treatments can continue to alter the colouring.
Maker-Mends Ltd can supply diamonds of any grade, colour, cut and clarity with or without certificates.
For further information
please contact David Lewis:
For any product fabricated from rough diamonds mined from January 1, 2003 onward, the seller warrants that the diamonds have been purchased from legitimate sources not involved in funding conflict and are in compliance with United Nation resolutions. The seller hereby guarantees that the diamonds are conflict free, based on personal knowledge and/or written guarantees provided by the supplier of these diamonds.
For any product fabricated from rough diamonds mined prior to January 1, 2003, the seller warrants that conflict diamonds will not be knowingly sold and that, to the best of their ability, will undertake reasonable measures to help prevent the sale of conflict diamonds in this country.
Lab Grown Diamonds- these are synthetic diamonds created in a laboratory, a synthetic diamond is a true diamond - pure carbon, crystallised in isotropic 3D form. The term synthetic describes any material that is produced in a laboratory through chemical-physical processes created by a human controlled process.
They are cheaper, of better clarity and unless being examined by an expert, indistinguishable from natural diamonds. Once scientists discovered that diamonds were formed from pure carbon they set about trying to create diamonds from cheap carbon. Diamonds have been created in a lab since the 1950's.
The largest gem diamond ever found was a 3,106 carat diamond. It was discovered in 1905 at the Premier mines in South Africa by Frederick Wells, a mine superintendent who received $10,000 for his find. The diamond was named Cullinan, after the mine's owner Sir Thomas Cullinan. The Cullinan I was the largest gem produced from the rough stone. It is a pear shaped stone of 530.2 carats and is the world's largest cut diamond. The Cullinan I is now in the head of the royal sceptre in the British crown jewels. The second largest cut diamond, the Cullinan II is a cushion-shaped stone weighing 317.4 carats and is set in the British imperial state crown.