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Dazzling diamonds: Mother Nature’s most mysterious and brilliant creation, a sparkling universal symbol of eternal love and commitment.




A geoglogical miracle

Diamonds were formed billions of years ago between 90 and 120 miles below the surface of the earth. Here, under phenomenal pressure and searing heat of between 900-1300 degrees C, carbon crystallised into the hardest material known to man: diamond. Diamond crystals were then forced to the earth’s surface by volcanic activity. They are found today in their rough form in rock deposits or shallow ancient river beds. 

The  4Cs (and one NAJ)

Buying a diamond is a life-defining moment you will never forget. To find the perfect diamond for you, you’ll need to visit a reputable jeweller who is a member of the NAJ. The expertise of your NAJ jeweller will give you the peace of mind and confidence to choose your perfect stone by explaining the 4Cs, the essential characteristics of diamonds.

Diamond comes out of the earth with two natural properties: colour and clarity, the first two Cs


The most sought-after white diamonds are colourless. They range from clear to slightly tinted. The closer to colourless your diamond is, the rarer and more valuable it will be.  


Under the massive pressure and intensity of heat involved in its creation, the carbon that forms a diamond will not always crystallise into a totally clear stone. Natural inclusions – nature’s own fingerprint – make each diamond a unique individual. However, the rarest and most valuable diamonds will have the fewest inclusions. Your NAJ expert will of course point out any inclusions which you cannot see with the naked eye.

The next two Cs……or what happens when we get our hands on it……


The skill of the diamond cutter and polisher unlocks the fire and brilliance in a rough diamond by polishing facets at precise angles so that the light reflects back from the diamond, revealing its brilliance. A well-cut diamond will blaze with all the colours of the spectrum.

The traditional round brilliant diamond might be the most popular shape but there are actually more than ten different shapes in all: a Princess cut, which is a square brilliant, an oval or pear-shape, a marquise or emerald cut, an Asscher or cushion, a radiant or even a heart shape. What this means is that you can choose a shape that really is personal to you. 

Carat weight

Diamonds are measured by weight in carats.

It’s an interesting word with an even more interesting story as it originally derived from the Greek word for a carob seed, which was once used to weigh diamonds due to its remarkably consistent weight.  Eventually, the seeds themselves were, unsurprisingly, phased out with a standard carat weight being established equal to 0.2 grams. 

The cutting process will mean losing some of the stone’s original rough weight to produce the fabulous polished diamond we all love today. 

Natural coloured diamonds

We think of diamonds as a colourless stone but they can come in an incredible array of different colours – canary yellows, chocolate browns, pinks, blues and greens to name but a few.

These are all rarer than colourless white diamonds but all share the same unique diamantine brilliance.


The colour and clarity of your stone will usually be determined by independent experts. While in the UK we use letters for colour and our own terminology to define clarity, the global diamond industry recognises a number of different grading systems. Different labs may use similar terms but might not be comparable so to take care when checking one report against another. It’s actually all fascinating stuff as your NAJ jeweller will happily explain!


The Kimberley Process was established in 2003 to challenge the trade in conflict or blood diamonds. Your NAJ retailer will have purchased diamonds from a supplier with a Kimberley Process Certificate, which will have tracked its journey from rough diamond into the supply chain where it is sorted, cut and polished. 

Choosing your perfect setting 

Having fallen in love with your perfect stone, you’ll want to work with your NAJ jeweller, taking advantage of their knowledge and expertise to find a setting to match. Don’t forget, there are no rules, no rights or wrongs to consider, just your own taste and personality. Share a little of your lifestyle and personaility with your NAJ jeweller and you’ll get the most important and beautiful purchase of your life just right!


© 2017
The National Association of Jewellers
Head Office: Federation House
10 Vyse Street
Birmingham, B18 6LT, UK

London Office: 45 Britton Street, London EC1M 5NA

Birmingham Office: 0121 237 1110
London Office: 020 7613 4445
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