The Four C’s of Diamond Grading

Cut, Colour, Clarity, Carat


Diamonds are measured by weight, the unit of scale is referred to as carat abbreviated ‘Ct’. One carat is equal to one fifth of a gram, and is based on the weight of a carob bean from ancient Egypt. Each carat is then divided into 100 points.

Within the industry, diamonds are also sold as units per carat. That is, if there are 10 diamonds each 10 points in weight, then they weigh in total one carat. Hence they are known as 10 per carat or 10 points. A 0.01ct is also known as a 100 per carat or 1 point, and 0.02ct is a 50 per carat or 2 points.

The price of diamonds is based upon rarity; larger stones are rarer than smaller stones.

This means that the larger the stone the higher the price per carat.  A one-carat stone is much rarer than two half-carat stones, and is therefore generally more than twice as expensive.

It has been suggested that it takes approximately 80 tons of ore to find a crystal large enough to cut a 1ct plus diamond.
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Many people consider all diamonds to be colourless. In fact, diamonds come in every colour of the rainbow, as well as Black! Moreover, they come in varying degrees of intensity of each and every colour.

The most sought after diamonds are those that have no colour. It is this lack of colour that makes these diamonds the most valuable.

Eternity Diamonds are available in colours D through to I.  The finest colour is known as ‘D’ colour, and as other colours taint this pure whiteness, the colour grade of a diamond is decreased. The following table outlines the colour grading scales used within the Australian and New Zealand industry.

From ‘D’ to ‘I’ the stones appear white to whitish. The subtle white tone change is very slight and can be compared to the different tones of white paper you may have on your desk.  As we proceed down the list you will notice that either yellow or brown can taint the whiteness of diamonds.

It is critical that the colour grade be correct!  Diamond colour is determined via a visual assessment and/or with the aid of an electronic colour-grading machine.  Visual assessment is undertaken using a known set of master stones to compare against.

In addition to the visual process Eternity Finely Cut Diamonds are also graded on an electronic colour-grading machine that ‘reads’ the diamond colour and prints the grade onto a card. Since the human eye is not as accurate as the machine, the grade is printed as a bar onto the report card, indicating the natural variance that the eye would not detect.


Eternity Finely Cut Diamonds are graded to internationally recognised standards, and are cross-checked by at least 3 qualified diamond graders. These three separate graders must agree on the final clarity and examine every Eternity Diamond.  This is your assurance that you are getting exactly what is specified. 

The most popular clarity of diamonds for Eternity Diamonds engagement rings is between VS1 and SI2.  In these grades, imperfections cannot be seen with the unaided eye and are still at a price that is deemed affordable by consumers at large. 

Clarity refers to the level of inclusions, in other words the degree of natural imperfections a diamond possesses.  Few things in nature are absolutely perfect and diamonds are no exception. Diamonds may have internal inclusions or external blemishes that are often referred to as natures fingerprint.   

These inclusions can affect the brilliance of a diamond as they may interfere with the refraction of light within the stone.  The fewer inclusions, the rarer and more valuable the diamond.  Diamonds are clarity graded under a special fully corrected triplet x10 magnifying loupe. However, further examination of very clean stones is done under a binocular microscope. 

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Cut more than any other of the 4C’s will give Eternity Diamonds the sparkle and scintillation that you are looking for.  At Eternity Diamonds cut is our niche- and we pride ourselves on producing the highest quality cut diamonds.

The sad truth is that many diamonds today are not cut as well as they could be. Many cutters choose to sacrifice some of the diamond’s beauty and fire to achieve a stone that is either a higher carat weight or a larger diameter.  We do not adopt this approach at Eternity Diamonds and will always choose a beautiful stone over a large unappealing stone. 

Cut, more than any other characteristic, gives the diamond its sparkle.

As you can see below, when all the angles are correct, the light that enters is dispersed back through the diamond’s top facets. When a stone is cut too shallow or too deep, the light that enters through the top is allowed to escape through the bottom and does not allow the maximum beauty of the diamond to be realised.

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Hearts and Arrows Diamonds are the most beautiful diamonds in the world.


Hearts and Arrows are not for everyone. They are for the individual that seeks the best in everything and won’t settle for second best. True Hearts & Arrows are rare and limited in production; so only select jewellers can offer them. You can own a masterpiece that is extraordinary in brilliance and sparkle like none other. No ordinary diamond can match the fire it will light in a woman’s heart.

Hearts and Arrows Diamonds are cut to ideal proportions with superior optical symmetry and a specific faceting pattern. When all these factors are in harmony the result is a repeatable, near perfect pattern of eight symmetrical arrows in the face up position, and eight symmetrical hearts when viewed in the table down position.


Eternity Diamond’s certificate is issued following an unbiased and professional examination to authenticate a diamond’s attributes. The carat weight, colour and clarity are all recorded on the certificate and the natural inclusions are also indicated on a diagram of the diamond: this is called diamond plotting. The certificate also shows the diamonds exact measurements in both mm size and percentages.

A Diamond Certificate will also indicate the cut of the diamond. Cut is particularly important as it determines the brilliance and radiance of the stone.

The overall quality of cut is determined by the combination of ‘Cut Proportion’, ‘Cut Symmetry’ & ‘Polish’.  Together the three describe the overall cut of the diamond. 

– Proportion refers to the measurements of the facets, the number of facets & the diamonds overall dimensions.

– Symmetry refers to the alignment and balance of the facets.

– Polish refers to the overall finish of the surface of the diamond.

All Eternity Finely Cut Diamonds will show a minimum of ‘very good’ or ‘excellent’ in ‘cut proportion, ‘cut symmetry’ and ‘polish’.

All Eternity Hearts & Arrows Diamonds will display ‘excellent’ in all three areas.  A diamond of this quality is sometimes referred to as ‘Triple Excellent’.

Are all Diamond Reports the same?

An unbiased, independent diamond certificate is the most important element when selecting a diamond.  An Eternity Diamond certificate guarantees and stands behind the quality of the graded diamond giving you the confidence to make that very special diamond purchase.

Not all certificates are the same. 

For example the Gemmological Institute of America (GIA) state the following on their report:

“This Report is not a guarantee, valuation or appraisal, and the laboratory providing this report (GIA) has made no representation or warranty regarding this Report, the diamond described herein or any inscription thereon”.

The GIA have many grading laboratories worldwide which makes consistent quality control difficult.  We have seen this recently with a wide recall on incorrect GIA Diamond Reports.  Coupled with the fact that the GIA will no longer provide you or your client with a reprint should your ‘Diamond Report’ be lost or damaged, the value of a GIA Report has become seriously degraded. 

However, as some of our markets demand GIA certified goods we do have GIA certify a percentage of our Eternity Diamonds.  All GIA certified diamonds are then independently recertified by the Australian Diamond Grading Laboratory in Australia to ensure they comply with our strict regulations of grading, and to offer our unique customer guarantee.

Certification or Branding?

‘Certificate Pretty’

Diamond certificates are great for documenting the colour, clarity and carat weight of your diamond.  They are not so helpful when it comes to the effects of fluorescence on the look of the diamond or the type or placement of the internal inclusions.  These characteristics are difficult to document and further adds to the risk of buying an unseen diamond online.   

It is also important to understand the term ‘cutting to certificate specifications’.  The majority of white diamonds are cut according to computer specifications.  These specifications can be altered and set up to the user’s preference.  It is considered normal for different gem labs to have different specifications or rather ‘wider set’ specifications that identify a stone as ‘excellent’ or ‘very good’ for example.  In other words one laboratories ‘excellent’ may only be considered ‘very good’ by another.

This variation in specs from one lab to another can possibly degrade a diamond certificates usefulness in defining cut. ‘Cut’ is one of the most important elements in ensuring a high quality radiant diamond.

Diamonds that look good on paper but not when you see them are often referred to as ‘Certificate Pretty’ stones.  This is where diamond branding becomes important. A branded diamond has its own built in quality control.  With a minimum of VG for Finely Cut and EX for Hearts & Arrows, individually selected and independently graded, an Eternity Diamond is a no risk purchase and a guarantee of exceptional quality.






Remember: diamond prices can differ as much as 10% from one colour or clarity grade to another, before taking into account the changes in price caused by other factors. Therefore it is essential that you ensure you are getting what you have asked and paid for.

Most diamonds are cut to individually set computer specifications that differ from one lab to the next. Diamond laboratories are not limited by uniform industry standards.  Each laboratory sets its own policy on how ‘strictly’ or ‘loosely’ they will grade their diamonds. 

When a diamond price seems too good to be true- it usually is.

A high quality Hearts & Arrows diamond is exactly as described.  It requires a high level of expertise and care to cut to this quality of symmetry, and requires the diamond cutter to commit to the possibility of loss of finished diamond weight or rough diamond loss to ensure they cut to these exacting standards.  Most diamond cutters focus on ‘yield’, Hearts & Arrows cutters focus on quality.

This is why purchasing a branded Eternity Diamond is your guarantee of quality.  


Branding reputation is extremely important and a brand will value and guard their good name at all times.  It is often impossible to hold a certification laboratory or online seller accountable for a less than perfect diamond.  Whereas it is relatively easy in our world of social media to hold a quality brand to account for their name and product.

 Unlike a GIA certified diamond which states that it is just the diamond laboratories ‘opinion’ of the stone we guarantee that our Eternity Diamonds & Eternity Hearts & Arrows Diamonds are as described every time.


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