The cubic modification of the chemical element carbon is called diamond. So much for the relatively sober depiction of a material that has fascinated people for thousands of years. Whether in the crown jewels of the English royal house or the countless mythical legends and stories, diamonds have become an integral part of human history.
In the following paragraphs we would like to give you a brief insight into the exciting field of gemmology. To this end, we first deal with the etymological and historical background of the diamond. Go then on its natural and The synthetic creation process is used to explain its value and the closely related 4 Cs (Cut, Clarity, Colour, Carat) in more detail. In addition, the most popular types of cuts for diamond jewellery are presented and an overview is given of the about the most precious and famous diamonds in the world.
Finally, we critically examine the methodology of diamond determination and give valuable tips and tricks.
Etymology and historical background
The word diamond is derived from the late Latin term
The oldest recorded diamond finds date back to the year 4000 BC. However, diamonds were neither worked nor used as tools in India because they were believed to lose their magical effect. That Diamonds were only discovered in the 13th century A.D. when they were processed and therefore also grinded. The diamond cut, which is common today and almost typical of diamonds, was even developed only in 1910.
As a rule, diamonds form only in the Earth's mantle and only between depths of 150 and 660 kilometres. Only here prevails the right pressure-heat combination in combination with sufficient carbon (graphite) deposits that diamonds on natural ways can arise.
Since mining at such depths is almost impossible, it is necessary to transport the stones naturally for industrial extraction. Volcanoes usually produce diamonds by eruptions at, or near, the earth's surface. Only through these natural processes is the industrial mining of diamonds possible at all. Comet impacts can also lead to the formation of diamonds. However, the diamonds found in and around the craters are much more too small for the use of gemstones.
In 1953 the physicist Erik Lundblad succeeded for the first time in producing a diamond synthetically. Since 1955 it has been possible to produce diamonds artificially using the high-pressure, high-temperature process. The basic material graphite is produced by the addition of a Catalyst for acceleration, compressed by means of a hydraulic press under such high pressure (60000 bar) that graphite is transformed into diamond by pressure and heat. Despite the addition of catalysts, the process takes a long time. of the conversion for a few more weeks.
Diamonds can also be produced by detonation synthesis or shock wave synthesis. Both processes use explosives to generate the necessary pressure and heat for the conversion process.
The diamond's value as a gemstone is due to its extraordinary light refraction properties, its enormous shine and its striking dispersion. These properties are best used in brilliant cutting to achieve maximum light reflection. and create the often quoted "fire" in the eye of the beholder.
The standard number of facets in brilliant cut is 57 (58 if the lower tip of the diamond is counted as a surface).
An ideal cut directs the light via the panel (upper surface) into the interior of the diamond. The Halefis or calette edges at the bottom reflect the light rays to the opposite side and thus prevent the light wave from escaping. The light wave is output via the upper facets of the diamond, which produce the typical sparkle.
A diamondaire, however, always faces the same dilemma with every rough diamond. On the one hand, the profitability of the diamond increases with the quality of the cut, but at the same time reduces it due to the inevitable loss of weight. Weight loss of a rough diamond to an "ideal cut" can be up to 70%.
The 4 Cs
Four properties determine the value of a diamond, also known as the 4 Cs. (Cut, Clarity, Carat, Colour).
The following paragraph briefly describes the value-determining properties of a diamond.
Only the cut transforms raw crystals into sparkling gemstones. For centuries, the techniques for refining this rare material have been further developed to ignite the fire in diamonds.
Basically, a decision is made between two styles. A rough gemstone can either be faceted or polished.
During faceting, the raw crystal is brought into the typical geometric shape that leads to optimal refraction of light. Non-faceted gemstones, such as the typical cabochon cut, have round shapes that are polished using a special polishing technique. is achieved.
With faceted diamonds, the so-called quality class of the cut is divided into five stages.
Quality grades of the cut
- Ideal grinding (optimum proportion ratios ensure maximum brilliance)
- Very good (Excellent proportions and brilliance, hardly any external features)
- Good (few external characteristics, good brilliance but proportions with slight deviations)
- Medium (reduced brilliance, increased external characteristics and significant proportional variation)
- Low (strongly reduced brilliance, clear proportional deviations as well as numerous and/or large deviations)
Inclusions and other optical properties of rough diamonds have led to the development of various types of cuts. Brilliance, lustre and colouring are not the only value-determining properties of diamonds, but also their weight, indicated in carats. A diamond grinder has not only the task to grind a diamond in the highest quality class but also to decide for a type of grinding, which is as high as possible in the total weight of the stone. results.
The following part b) gives a brief overview of the possible types of cuts.
Types of cut of the diamond
antique cushion cut
As already briefly mentioned before, the so-called carat indicates the mass, i.e. the weight, of gemstones. A metric carat is 0.2g.
The weight of the carat has its origin in the dried seed of the carob tree, since it was previously considered to be very constant in weight and size and could therefore serve as a reference.
Today, the weight of a diamond is measured with an accuracy of one hundredth. A carat is therefore divided into 100 points which are assigned to the corresponding exact weight unit. A diamond with 50 points weighs exactly half a carat. Unfortunately the carat has no legal unit sign so there are several abbreviations in circulation. In Germany, the carat number is usually indicated as "Kt". In Austria and Switzerland, "ct" is the carat number.
The colouring of the rare mineral also has an influence on its value. The so-called "colour designation" of the diamond begins with the letter D. A diamond with this colour designation is absolutely colourless and represents the best possible degree. The colour designations come from the GIA (Gemological Institute of America), a research institute founded in 1931. The colour scale ranges from D (ultra-fine white) to Z (maximum tinted yellow). The following table gives an overview about the shades still referred to by the GIA as white (1-11).
|Nat. name||Int. name||GIA designation||Occurrence||Hue||Colour scale|
|1.||Superfine White+||River||D||very rare||colourless|
|2.||Superfine White||River||E||very rare||colourless|
|3.||Fine White+||Top Wesselton||F||very rare||colourless|
|4.||Fine White||Top Wesselton||G||rare||almost colorless|
|6.||Lightly tinted white+||Top Crystal||I||rare||almost colorless|
|7.||Lightly tinted white||Top Crystal||J||rare||almost colorless|
|8.||Tinted White+||Crystal||K||rare||tinted white|
|9.||Tinted White||Crystal||L||rare||tinted white|
|10.||Tinted 1||Top Cape||M, N||abundantly available||tinted|
|11.||Tinted 2||Cape||O||abundantly available||tinted|
The degree of "purity" of a diamond is significantly influenced by the inclusions or impurities in the stone. A diamond is described as "fl" (flawless), i.e. "absolute" pure, if the eyes of an expert, even at 10x magnification I can't see any inclusions. The following table gives a brief overview of the various purity classifications of the diamond.
|fl||flawless||Flawless even at 10x magnification (no inclusions or external defects visible)|
|if||internally flawless||Except for possible surface traces from the processing of flawless interior|
|vvs1/vvsi||very, very small inclusions||Even at tenfold magnification, inclusions are very, very difficult to detect.|
|vvs2||very, very small inclusions||Even at tenfold magnification, inclusions are very difficult to detect.|
|vs1/vsi||very small inclusions||Inclusions are difficult to detect at ten times magnification.|
|vs2||very small inclusions||Inclusions are visible at tenfold magnification.|
|si1||small inclusions||Inclusions are easily recognized at tenfold magnification.|
|si2||small inclusions||Inclusions are very easy to see at tenfold magnification, but not with the naked eye.|
|pi1||Piqué I||Einschlüsse mit bloßem Auge sehr schwer erkennbar, mindern die Brillanz jedoch nicht.|
|pi2||Piqué II||Inclusions visible to the naked eye, only weakly reduce brilliance|
|pi3||Piqué III||Inclusions are easily visible to the naked eye and significantly reduce brilliance.|
The most precious diamonds in the world
|Culligan||Biggest diamond ever found. Split into a total of 105 stones, the largest 9 pieces form an elementary part of the British crown jewels.||3016,7|
|Excelsior||Found in South Africa, it is the second largest diamond ever found and was split into a total of 22 stones. The largest of these weighs a proud 373.75 carats and is owned by Robert Mouawad.||995,2|
|Star of Sierra Leone||Was discovered in 1972 in Sierra Leone. With a gross weight of 193.78 grams, it is the third largest diamond ever found in the world.||968,9|
|Golden Jubilee||It's the largest cut diamond in the world. In 1985 he was promoted in South Africa and after one year of work he retained an incredible weight of 545.67 carats. In 1995 he received the blessing of Pope John Paul II and is is now part of Thailand's crown jewels.||755|
|Orloff||Sitting in the golden sceptre of the Russian tsar and today can be seen in the Diamond Fund Exposition in the Kremlin, Moscow. According to legend, it was stolen from the eye of the Indian statue of Brahama the god who cursed it. that he had been.||189,62|
|Koh-i.Noor||It is not known when the Koh-i-Noor was found. However, his place of discovery was most probably in India. Today he lies in the Tower of London.||186|
|Hope Diamant||His discovery year is also unknown. The brilliant blue diamond first appeared in history in 1642. He is also said to have been in the possession of the self-proclaimed Sun King Louis XVI.||45,52|
|Green Dresden||The largest naturally green cut diamond. Its bright green color results from the naturally occurring radioactivity of its deposit. Today he can visit the "New Green Vault" in the Residenzschloss Dresden. will be.||41|
Identification of real stones
It comes again and again before the gemstone jewelry from an old family estate is found. So the question immediately arises, are the stones real? Is it possible to determine this from home under the living room lamp?
In times of economic crises and high inflation rates, diamonds are all too often referred to as a "safe" investment. But how do I know, as a possible layman, if I will get a real diamond sent to me, and if the figure is also is the true value.
At this point we would like to point out that nowadays it is very difficult, if not impossible, for a layman to define a diamond as "real", i.e. as a natural product created over millions of years. This is clearly due to the centuries long endeavor and ultimately also the success of "science" to produce diamonds artificially. Whether this is due to the pursuit of money and power or to the drive for industrial progress may be discussed elsewhere. will be. However, we always advise you to visit your trustworthy jeweller for a determination of authenticity and then not to lose sight of your own stone.
In the next paragraph, a small overview of the possible determination methods is given and their risks and grey areas are explained.
There are ways and methods to distinguish a real diamond from the most famous imitation diamond, the zirconia.
A real diamond of the same size is much lighter than a zirconia. This is due to the lower density of the diamond. A real one carat diamond in brilliant cut has a diameter of 6.5mm. A Zirconia in the same cut and weight comes only to a diameter of 5.4mm. This principle also works the other way round. If you have two stones with the same diameter, the diamond will always be much lighter than the zircon.
The problem with this method, however, is that one must first have a certified real diamond with the same weight as the specimen to be checked in order to be able to produce comparative values. There is also the problem of the quality of the cut. It can significantly influence the diameter of the stone with the same carat number.
The Glass Test
According to popular belief, distinguishing a zirconia from a diamond can perform a glass cutting test. Because a diamond can cut glass, but a zircon cannot. However, this is clearly not the case. High-quality zircons are is able to cut through glass. This test is therefore not suitable for checking whether it is a zirconia or a real diamond.
The breaking test
Do not hit the stone with a hard object to check its authenticity. Although diamond is the hardest natural material we know of, it is still relatively easy to split. This is due to its molecular structure of the diamond. Parallel grid bonds define the breaking edges.
The condensation test
When breathing on glass panes, the moisture stored in our breath remains and condenses. This also happens with real diamonds, but the condensation humidity only lasts for a fraction of the time. Should one of you If the gemstone is clearly fogged up, you can assume that it is not a real diamond.
The water drop test
If a drop of water is added to the tablet of the stone, a high, arched dome forms in real diamonds. A zirconia cannot do this. A drop of water melts on its board.
The luminous calculability
Take a white sheet of paper and draw a straight line on it with a pencil. Now take your gemstone and place it on the line with the blackboard facing down. If you want to see the line (given If broken) it is around a zirconia. Real diamonds have such a high refractive index that you cannot see through them.
The atomic structure of diamonds ensures extraordinarily good heat conduction. As a result, real diamonds always feel cold because they absorb the heat of our skin immediately. Zirconia have extremely poor heat conducting properties. Properties.
Distinguishing diamonds from other stones
The most difficult "diamond double" to recognize is the moissanite. Even experts find it difficult to distinguish between moissanite and real diamonds. A diamond tester will always show a real diamond although a moissantite is a real diamond. is tested due to the almost identical thermal conductivity of the moissanite. This is due to the almost identical thermal conductivity of the moissanite. A moissanite also passes the density test described above, as the mass behavior is very similar. It is also approximately the same hard as real diamond and can reach a value of 9.25 on the Mohs hardness scale. Moissanites and diamonds also show the same results in the condensation test and water droplet test. Special moissantite test devices are used for constantly improved. But even they cannot deliver a really reliable result, as the production processes for moissanite are constantly improving. Only the light calculation index is able to reveal the moissanite, since it has birefringent refractive properties. This ultimately leads to facet doubling and the moissanite even sparkles slightly more than the real diamond. However, a very strong microscope is required. and the trained eye of a specialist to determine the effect of facet doubling. With small stones under 2mm or even with clearly larger but set stones a differentiation is not doubtless possible.
Loosely set stones can be tested in Dijomethan without any doubt. Since diamond has a density of 3.52, moissanite a density of 3.21 and dijomethane a density of 3.32, the diamond sinks. The moissantite, on the other hand, floats on the surface. As always, the devil lies in the detail. The dijomethane density test requires unmounted stones.
A real diamond does not refract the light in its individual spectral colours but reflects it almost unbrokenly. The sparkle of a real diamond is therefore colourless. A zircon, on the other hand, reflects a wide spectrum of colours, but mostly a light orange-red glow.
Contrary to the mistaken belief that sapphires are always blue, sapphires actually occur in almost every colour. With a Mohs hardness of 9, they are somewhat softer and thus also more mass poor than diamonds. White or colourless sapphires do not have the same hardness as real sapphires. Diamond typical light-dark contrast in itself. If the inner color play between light and dark shows rather flowing than sharp transitions, it may be a white sapphire.
The white topaz
In contrast to diamonds, white topaz is much softer. A diamond is one of the hardest materials known to mankind. So it is quite unlikely to see scratches on a diamond. If scratches should be recognizable, it is a matter of is unlikely to be a real diamond, but a topaz.
Especially when diamonds are considered as investments, they should never be purchased without a certificate. Trustworthy certificates of authenticity that provide information about the DNA of a diamond are only issued by the GIA (Gemological Institute of America), the AGS (American Gem Society) of EGL (European Gemological Labratory) and the IGI (International Gemological Institute).
For more detailed information about the individual institutes, we have compiled the respective web links for you here.
If for any reason no certificate is available, we expressly advise against a purchase. Only a verifiable find before 1953, i.e. the date of manufacture of the first successfully synthetically produced diamond, then offers a Security.
- Main image diamond: iStock.com/Shenki
- Cut types of the diamond: Leysan/stock.adobe.com
- Johannisbrot cavern: emuck/stock.adobe.com