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Diamonds by David Stockenstroom

WHAT IS A DIAMOND WHERE ARE THEY FOUND.

The word diamond is derived from the Greek word Adamas which means unquonquerable. There is nothing on this planet that is comparable to its hardness. It is 140 times more resistant to cutting than corundum (ruby or sapphire) which is the next hardest stone on the Mohs scale of hardness. It would seem that this stone is very special indeed yet its chemical composition is pure carbon ie. coal. Diamonds were formed millions of years ago under extreme pressure and heat. Mostly found in extinct volcanic formations where the pipe of the volcano is usually filled with a rock type called Kimberlite which is rich  in diamond crystal. In ancient times most diamonds were found in alluvial deposits, which is above ground but with more technology underground diamonds were mined. Also rivers were a great source of diamond as they usually originated from a source close to an extinct volcano were with years of erosion caused many to dislodge and travel downstream. Many diamond were found this way in earlier times. The largest exporter of diamonds of the ancient world was India. Only to be surpassed by Brazil in the 1800s and then by South Africa at the turn of the last century.   Today they are found all over the world in most parts of central and sub Saharan Africa to Russia, the United States,Canada, South America and even Australia.

WHAT MAKES A DIAMOND GOOD OR BAD?

About 80% of all diamonds mined are used in industry. From the manufacture of cars to surgical and dental instruments. Only 20% of all diamonds mined are considered gem quality. The first way to assess a gem quality diamond is by looking at what is commonly known as the 4 C’s this is an international grading standard using a X10 jewellers loupe. they are:

COLOUR

Most gem quality diamonds are found in the white to yellow colour spectrum. Although diamonds do occur in a variety of colours with are known as natural fancys, these are extremely rare and are not classified in the same way as most commercial stones. The diamond colour scale works with letters of the alphabet starting at colour D and ending in Z. colour D is the most desirable as it is the whitest of colours  with value going down the closer one gets to Z. very rarely do we see Diamonds used in jewellery beyond colour N as anything over this colour is not at all popular with the market so the value of these stones are not very high. To determine the colour grading of a diamond a polished or rough stone is placed in a light box and a set of “master stones” are used to compare the colour. The master stones are normally synthetic stones of varying colour from D to H. the grader then basis his/ her colour judgement by comparing the diamond to the colour spectrum on the stones in the box. As one can tell this process is not scientific but with skill and years of training it becomes second nature to most graders. Depending on the colour the closer to D the more valuable the diamond is. On the extreme side to this is the valuing of Natural fancy diamonds which are far more rarer than commercial white stones. So what this means is that a diamond of the same carat weight classified a colour D versus a diamond of the same size certified as a natural fancy yellow will be worth less money than the natural fancy yellow because of the colour stones rarerity. Colour diamonds also vary in prices from each other depending on fashion and also rarity. Pink diamonds today are considered to be the most expensive fancy colour on the market with the highest price paid at Christies New York for a pink diamond was $83 million just over 1.1billion rand in our money for 59.6 carats.

CLARITY

This refers to the diamonds degree of perfection. When louping a diamond through a X10 magnification a grader will assess the stone to see if there are any inclusions in the stone or on the surface. This grading is a little bit more accurate that colour grading as the formula is pretty standard where colour is sometimes if not most times a matter of opinion. If there are no inclutions visible with the naked eye through a X10 magnification loupe inside or on the surface of the stone it is considered flawless. If there are minor surface imperfections (which in most cases can be removed by polishing) the stone is classified as internally flawless. The scale moves all the way down I1-3. See chart provided. An inclusion is a natural spot which may be carbon or tiny bubbles which are called feathers. Sometimes they are also cleavage cracks  called feathers. Marks on the surface of the stone are also called inclusions, but these can be mostly polished out. The less inclusions the stone has the more perfect it is and therefore the more valuable the diamond is.

CUT

Diamonds are cut in a variety of shapes. The most popular being the round brilliant cut. The skill required by a diamond cutter is a combination of mathematics and artistry. In the old days and sometimes even now for larger stones the diamond is cut by hand using a cuyying wheel and diamond powder which slowly erodes the crystal until a facet is formed at the precise angle the cutter is trying to achieve this is done by hand until all 58 facets are polished creating the modern brilliant cut. Most antiques jewellery containing diamond are what we call old European cuts which have fewer facets than modern brilliant cuts. There are also rose cuts  and eight cuts among many but these are the cuts that we mainly find in antique settings. This is also how we can tell if a piece is old or modern. See attachment of different cuts.

CARAT

This is the weight of the stone. In the ancient days they used the seeds of a carob tree as a measuring unit as the seeds are quite uniform in weight, hence the name carat. Today a more international standard of measurement is used. 1 ounce is equal to 142 carats. That is 1 carat is equal to 0.2grams. the carat is divided into 100 points therefore a half a carat is 50 points or 0.50ct.

THE BEST DIAMONDS?

Well as by now you can tell the best diamond would be a perfectly cut, flawless, colour D with a large caratage! The wonderful thing about a diamonds size and value is that the differences can be quite astronomical for example a 1 carat colour D FL perfectly cut could sell for R100 000 a 2 carat single stone colour D FL perfectly cut could sell for R350 000. This is because the larger the stone the rarer. It takes between 200-250 tons of rock to sort through in order to find 1 carat of diamonds. That equates to one quarter of a million kilograms of dirt to find 0.2g of diamonds!

Of course due to its rarerity diamonds have been copied and faked for centuries. Here are some of the stones that are used to simulate it please note that some of these are synthetic and not natural.

Paste: this is a high density lead glass that was the most common synthetic used to simulate diamonds. It was used for centuries and is still used in the manufacture of costume jewellery.

Synthetic spinel and synthetic sapphire: these are lab grown stones and are colourless and also used to simulate diamonds.

White topaz, rock crystal and zircon were also used to simulate diamonds

Moissanite: this is a synthetic stone that is closest in composition to diamond some diamond testers also can’t distinguish between real diamonds and moissanite. These are very rare on the market because they cost a lot to manufacture but a trained professional can easily tell the difference by using a microscope or refractive index test.

Diamonds are also colour enhanced by a process called irradiation (heat treatment). A diamond lab can easily detect if a diamond has been heat treated for colour and these stones are not as valuable as their natural counter part.

How do you tell a real diamond from a fake?

We typically use a diamond tester but with years of experience one can generally tell through a loupe. This is not something that I would encourage a novice to do rather take it to the experts!

 

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