Remark: all the diamonds put on sale on the site " Gemfrance " were acquired with justifiable sources not involved in the financing of conflicts, according to the resolutions of the United Nations. We guarantee that these diamonds are not native of zones of conflicts, guarantee based on our knowledge or on written guarantees of the suppliers of these diamonds.
The diamond: a stone which everybody knows, prestigious and nevertheless so complicated!
It is "the archetypal precious stone". According to the former terminology, there are four precious stones: the diamond, the ruby, the sapphire, the emerald.
The diamond is known and used since Antiquity. Its name comes from the Greek mount " Adamas " which means invincible, unbreakable.
A name completes because it is the hardest material known this day, 10/10 on the scale of Mohs. A diamond can be thus crossed off only by another diamond
Its hardness comes from its structure: 100 % of carbon.
The diamond is the metastable shape some carbon in the normal conditions of temperature and pressure. In its natural state, it possesses a cubic structure with centered faces and eight atoms by conventional stitch.
The structure of the diamond results from covalent connections (thus strong) and directional, where every atom is bound in a tétraédrique way to its closest four neighbors (hybridization sp3 ' some carbon).
He burns only in the pure oxygen and in very high-temperature.
He has a high thermal conductivity, between 1000 and 2600 W/(m · K), while his electric conductivity is low.
Other atoms (Nitrogen, Borates, Hydrogenates) can skip into its structure and be the causes of a color other than white: yellow, orange, pink, red, brown (Cognac, Champagne), blue, green, black, purple
The evaluation of the price of a diamond takes place according to four criteria, which we are in the habit of calling 4C: the color ( Color), the weight (Carat), the purity ( Clarity) and the size ( Cut).
The color:
The color the most often met remains the (colorless) white, but he is not always a pure white. He is often with a yellow more yellow tint which influences the value of the diamond, because the pure white diamond is the most sought.
It was created that a scale to classify the color of the diamond which goes from the white ( D-E-F) to the yellow colored ( Z ).
By means of diamond of comparison (selected and classified E, F, G, etc.), we are going to be able to compare the diamond and thus classify it.
The weight:
It is the weight in carats of the diamond.
The carat of a diamond is extremely important: it is the major criterion to define the price.
Below a certain weight, when stones are very small, we call them the "mixed", mainly for the pavement. As soon as we cross the symbolic bar of the carat of 0.99ct in 1ct, or 2.99ct in 3ct, the price is much higher in the carat.
There is a precise correspondence between the diameter of a diamond and the weight, for perfectly cut stones.
This below the picture of the weights of the round diamonds " size glittering " according to their diameter
Indicative dimensions of diamonds according to their weight.
The purity:
The purity is going to depend on the quantity of inclusions in the stone. The ideal is a diamond without any visible inclusion in the magnifying glass of swelling x10.
A scale of purity exists to be able to classify diamonds. We classify stones according to the inclusions there which we see or not in the naked eye and in the magnifying glass x10. The microscope serves only confirmation. Graduation VVS, VS and If can be subdivided into 1 or 2 only for the diamonds furthermore of 0.47ct.
The size:
We study the proportions of the diamond as well as the quality of the polishing.
Are the ideal proportions of size of the diamond respected? Are there additional facets or not? The diamond has to be very round, the breech has to be centered well, the diamond has to be neither too deep nor too flat, otherwise the light does not stand out, as shows it the plan below.
In a well cut diamond, the light returns by the table, is refracted on a side of the breech, then, on an other side, before standing out by the table. If a diamond is badly cut, a part of the light entrante is not going to stand out by the table, where from a lack of shine.
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History:
The diamond is more one of hurdy-gurdies stones known about the world. It was reserved for a long time for kings and in the middle member of a religious order. It was a symbol of power and hierarchy in the society. In a way, it is always the case today. For Greek diamonds were the tears of the gods and represented the immortality.
The first discovered and exploited mines were in India towards approximately 2000 BC. The most famous being the mines of Golconde, where from the most beautiful diamonds went out, in particular current "Blue Hope", the Regent, Sancy, diamond Archduke Jospeh, and many others.
Until XIVth century, Venice was the biggest center of trade of diamonds. Then, it was in the tour of Paris and Bruges, then finally of Antwerp (XVth century) that is it always. The journeys of the French explorer Jean-Baptiste Tavernier in India, allowed to return numerous diamonds and to promote it in Europe.
At the beginning of the XVIIIth century, Portuguese notice, by watching playing the gold panners in Brazil, that these use diamonds as tokens! In the region of Minas Gerais, in Brazil, begin then a harvest of another kind. Diamonds are mainly found in secondary sites, as the alluviums of rivers. Brazil produced a great deal of diamonds but deposits were fast overtaken by a new discovery.
In 1866, a child finds an attractive pebble by playing by the river Orange in South Africa. It is sent in London, where it is identified as a diamond. It is the very first: it makes 21ct and will be baptized "Eureka". On one year later, the second diamond is found in the region. Of 83.5ct, it is " Star of South Africa ". In 1867 opens the first diamond mine in South Africa, and it is a primary site! That is diamonds " go out of the ground to this place " they are not to transport and scattered somewhere else.
The mine of Kimberley, the most famous, produced not less than 14.5 million carats (approximately 3 tons) between 1871 and 1908. "Big Hole" as we called it, is a hole of 400m of diameter and of 1070m of deep. It was exploited in the hand by families which bought concessions of patches of land and dug to find diamonds. Become too dangerous, and more profitable, the mine was given up in 1914. It is the most important hole in the World dug by the man.
In South Africa, a monopoly settles down slowly and extends at the world level, that of the company Of Beers with a control of 80 % of the world production of diamonds
In 1905 is discovered the diamond which is always the biggest diamond to the world: "Cullinan", weighing 3106ct (env 621g).
South Africa becomes the first world producer of diamonds and will stay him during all XXth century.
At the end of the XXth century, emerge from other deposits in the world and thus from other one rival companies of it Of Beers, even if most of the raw products cross not the DTC (Diamonds Trading Company) in London, the owner of which is other than De Beers.
Russia, Australia, Canada (more recently), China, and a big part of Africa run away a place in the world production of diamonds in the XXth century. And the centers of businesses of the diamond scatter in the world. In New York, are sold the biggest diamonds; Tel Aviv, in Israel, is a technological pole of the diamond; Surat, in India, cuts mainly small diamonds. Antwerp remains renowned for its diamonds of high qualities.
In 2014, Russia passed in front of Bostwana as first producer of diamonds in the World. Canada is ranked third in front of Angola.
But, it is Lesotho which holds, in 2014, the record of the average price of diamonds with a 990.18-dollar value.
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Deposit and formation:
Most of the diamonds formed there is approximately 990 million years, some date even more than 4.2 million years.
Diamonds form in approximately 200km underground under the action of high temperatures (1700°C) and high pressures (55 in 60Kbars). They are going to surface thanks to volcanic phenomena which produce a rare type of called magma kimberlite. The kimberlite goes back up volcanic pipes called "pipes" and produces then what we call a "primary holiday cottage", it is the source of the diamond.
The appearances of the primary cottages (open-air or underground) ask for big infrastructures
.
We also find diamonds in secondary cottages. Further to the erosion, kimberlites disintegrates and release the diamonds which find themselves in alluviums transported by stones since the primary cottage. There are numerous home-made operations on the secondary cottages
In Namibia, diamonds are carried by rivers since South Africa which throw themselves into the sea. The research is made by means of enormous boats which pump the bottom of mouths. About 90 % of these diamonds are of qualities gemstones.
Every appearance in the world has more or less its "speciality". The appearance Cullinan (closed today) and The first one Mines in South Africa, are known for their blue diamonds.
The mine of Argyle, in Australia, is considered as its production of diamonds of pink and red color.
Some famous diamonds:
- Archiduc Joseph
- Beau Sancy
- Bleu de France
- Blue Hope
- Centenary
- Chah
- Cullinan
- Darya
- De Beers
- Etoile de Sierra Leone
- Eureka
- Excelsior
- Golden Jubilee
- Graff Pink
- Grand Moghol
- Incomparable
- Jonker
- Koh -i- Noor
- Kuh-I-Nur
- Lesedi la Rona
- Millenium Star
- Moussaieff Red
- Nizam
- Noor
- Oppenheimer Blue
- Orange
- Orloff
- Président Vargas
- Régent
- Spirit of De Grisogono
- Star of America
- Star of South Africa
- Taylor-Burton
- Tiffany
- Vert de Dresde
- Wittelsbach-Graff
- Woyie River
To know more about it, we recommend you the book Hardness 10 - The diamond, on sale on Gemfrance.com.
To know more about the Diamond, see Mindat.org->
