DIAMONDS

Diamonds are naturally occurring chunks of carbon whose atomic structure makes them the hardest substance on the planet and allows them to manipulate light in a way that has captured the imagination for centuries.

Today, they are the best known of all precious gemstones and have long been the popular choice for engagement.

Diamonds that have the natural properties of size, and the colour and clarity to be desirable as gemstones, are very rare. These properties are known as the 4 Cs: cut, clarity, carat (size), and colour. But how do you define these qualities and how does it help when buying diamonds?

Diamond Colour

99% of the time when we talk about diamonds’ colour, we are talking about white diamonds and the slight variations between them.  Diamonds come in many colours and these are known as fancy colours, but, although these are fascinating, they are incredibly rare, expensive, and not the subject of this article. 

The photograph above, courtesy of the GIA, shows the differences in colour between diamonds of certain grades. As you can see, at first the difference in colour is very subtle. However, as you go down the grades, the differences become more apparent.

White diamonds are graded on a scale from white to yellow.  White is considered the most desirable, while yellow are the least desirable.  As seen above, the scale goes from D to Z, in order of whitest to yellow. So, when you hear about a ‘D colour diamond’, somebody is talking about a diamond that is of the whitest colour we know of and, therefore, a very nice and valuable diamond

But why start at D rather than A? The scale starts at D in case whiter diamonds are ever found. So who knows, maybe one day we’ll be talking about A or B colour diamonds.

The diamond colour scale is split into 5 sections: colourless, near colourless, faint, very light, light. This is because only an experienced gemologist would be able to identify the difference between grades within these categories, making it prudent to group them together.

Cut

The cut is really two Cs in one. Firstly, there is the shape of the diamond, what is actually known as the cut. Diamonds can be cut into many shapes, though the most common is the round brilliant cut, which is done to maximise a diamond’s sparkle. There is the princess cut, which is a square, the baguette which is a rectangle and so on.

Pear cut diamonds

We love pear cut diamonds and specialise in sourcing them and making bespoke jewellery. Pear cuts have 57 facets and the shape adds classic elegance to any engagement ring.

As well as desribing the shape of the diamonds, the ‘cut’ also refers to how well the individual facets on a diamond are positioned and aligned. This is arguably the most important factor in determining how well a diamond sparkles and its overall look.

A diamond that is very symmetrical and has well aligned and polished facets will act like a hall of mirrors and reflect a lot of the light that enters it. When light enters a diamond, but is not reflected back out, it is lost and can result in dark spots within the stone.

When you look at a diamond grading certificate, it will describe the shape, for instance pear cut, and it will also grade the quality of the cut as well as grades for symmetry and polish.

Diamond proportions

As well as these grades for cut, symmetry, and polish, a GIA diamond certificate will also have a diagram, like the one on the right, which shows the proportions of the stone described on the certificate.

There are ideal proportions for the various different diamond cuts and the diagram helps to illustrate how close the stone is to these ideal proportions.

Clarity

The clarity of a diamond refers to how many natural inclusions it has. Until recently,  in the world of commercial diamonds, diamonds with inclusions visible to the naked eye have rarely been used. However, trends change, and diamonds with large visible inclusions, are now popular and you might know them as ‘salt and pepper diamond's’. Inclusions are like ‘birthmarks’, often where something has been trapped in the diamond during its formation.

Like with colour, there is a scale on which the clarity of diamonds is graded. This goes from F to I3. F means flawless and, again, these are the rarest and most valuable of stones. These stones have no inclusions that are visible under 10x magnification.

Inclusions or flaws are totally natural and often very hard to see.  Diamond cutters take the position of these inclusions into account when they are deciding which shape to cut a diamond crystal into.

It is generally accepted that a diamond that has a clarity grade of VVS2 or better will not have any inclusions that are visible to the naked eye.

Carat

When we talk about a diamond’s carat, we are talking about its weight.  Diamonds are weighed in carats and a carat is made up of 100 points. So, when you hear someone talking about a 50 pointer and ½ carat stone, they are talking about the same thing.

The carat unit of measurement derives from the carob seed and these seeds are remarkably uniform in weight, approximately ⅕ of a gram, which is the weight of a carat.

The more a diamond weighs, the more it will cost (all other factors being equal) and prices jump at certain levels, for instance at 1ct.  The diamond price curve is not a straight line; a 1ct diamond will be more than double the price of a ½ ct stone that has the same colour, clarity, and cut characteristics.

The diamond’s weight and spread (how big the stone looks when you are looking down on it ) have a relationship, though the depth of a diamond is important too. This means you could have two diamonds that looks the same from the top but are different weights.

The average weight for an engagement ring in the UK is around 0.70ct and a diamond’s weight will be noted on the diamond grading certificate.

Diamond certificate

Often a diamond will come with a certificate from a gemology laboratory.  The best known and most respected of these labs is the GIA, Gemmological Institute of America, though there are others, such as the IGI.

When a diamond has a certificate from one of these labs, it means that the stone has been assessed by a professional diamond grader under certain conditions and has been graded according to certain criteria.

Having a certificate from a lab will increase the value of the stone, especially if it is from the GIA.  This is partly because it costs money to have a diamond independently assed. However, if you have a diamond that does not have a certificate, you can send it to a lab to be graded.  It is also seen as a confirmation of the stone’s characteristics and gives buyers confidence.

All diamond grading reports are unique and cannot be replicated, so don’t lose it!

Why do we wear diamond engagement rings?

There are some solid practical reasons for wearing diamonds in engagement rings.  Diamonds are the hardest natural material on earth and are virtually scratch proof. As engagement rings are worn all of the time this really comes in handy.

Diamonds measure a 10 on the mohs scale of mineral hardness and they are 4 times as hard the mineral that comes in at 9, Corundum.

And, of course, they sparkle! This may sound obvious, but the way diamonds have captured and reflected light has captivated us for centuries.  Obviously these days we have smartphones in the palm of our hands that can display moving images and thousands of colours so we’ve become blasé about the visual phenomenon but imagine seeing a diamond back in the 1600’s . In a sense it’s a legacy of our fascination with nature and colour.

Fluorescence

One fascinating (and in my opinion underrated) natural property of diamonds is Fluorescence. Around 1 in 3 diamonds are naturally fluorescent and as you can see form the video below that we took at the Natural History Museum in London, this can be in a variety of colours.

Fluorescence in a diamond is normally considered a ‘defect’ and in rare examples can actually make a diamond appear ‘milky’ sometimes termed ‘fancy white’, however this subjective and some people enjoy this unique natural property of diamonds.

10 QUICK Diamond facts

1. A round brilliant cut diamond has 57 facets.

2. A D colour diamond is the best colour grade you can get.

3. D is the highest grade to allow for the addition of higher grades if whiter diamonds are found. 

4. As the world’s hardest mineral, they are perfect for wearing everyday.

5. Approximately 1 in 3 diamonds are naturally fluorescent.

6. Diamonds and other gemstones are weighed in carats; 1ct = .2 of a gram.

7. Diamond is the birthstone for April.

8. Diamonds form under intense heat and pressure approximately 100 miles under the earth surface.

9. The accuracy of the diamond’s cut affects its sparkle more than any other of the 4Cs.

10. Diamonds should be regularly valued for insurance.

Where do diamonds come from?

Diamonds are found and mined in several countries around the world. Most people are aware that diamonds come from Africa, and there are several African countries which have diamond mining industries however they are also found in Canada, Brazil, India and Russia. As of 2022, Russia was the world’s largest diamond producer, followed by Botswana, however, since the Russian invasion of Ukraine in February 2022, Russian diamonds are being excluded from the international market. Where a diamond is mined has a big impact on whether we consider it to have been ‘ethically sourced’. Ethically sourced diamonds (and all the other materials used in jewellery) are something we are passionate about and have written extensivley about, if you’re interested to learn more about the subject, click here.

Once a diamond has been mined, it goes to be sorted. Diamonds are sorted into parcels with stones that have roughly similar characteristics. This might be size, shape or colour and the sorting process is done in several places around the world, often close to the mines. London used to be a world centre for sorting rough diamonds however in 2012 De Beers moved their sorting operation to Gaborone, the capital of Botswana and today a large proportion of the diamonds mined by De Beers in Botswana, Namibia and South Africa are sorted here, bring skilled jobs to the country.

Once diamonds have been sorted they go to be cut. Today, the vast majority of the world’s diamond are cut in India. It’s estimated that there are around 1 million people employed in diamond cutting in Surat, where 90% of the world’s diamonds are cut. A small proportion of diamonds are still cut in New York, London, Belgium and Amsterdam.

After they have been cut, diamonds are sent to trading centres where wholesalers, buy and sell diamonds to jewellers and jewellery manufacturers ready to be sold onto consumers.

Diamond cutting

When a diamond comes out of the ground it is in its ‘rough’ state. Whilst some diamonds are mounted in jewellery in this state, the vast majority of diamonds are cut and polished before being set in jewellery and this process has a huge impact on how the finished diamond looks. For most people in the trade, ‘cut’ is the most important of the 4c’s.

The diamond cutting process is still done mostly by hand, with some help from technology

To the right, you can see a diamond being cut on a cutting wheel. The wheels are impregnated with diamond dust at various levels of coarseness and the excess materials is ground away.

Lab grown diamonds