Diamond Education

There’s so much more to diamond education than the mere understanding of the 4 C's of diamonds (color, cut, carat, clarity) and the factors that impact its quality and price.
Stay hooked to our website to get all enlightened about the nuances of diamond identification.

1. Carat

Pretty things may come in small boxes, but what’s in those boxes better be big. That is, yes, size does matter. However - carat weight is not the same thing as size - how large a diamond appears is also dictated by other factors such as shape and cut, so it is important to understand carat weight beyond the value it is generally and often mistakenly ascribed.

Diamond Carat Weight

Instead of grams or kilos, diamonds are weighed in carats (not to be confused with gold’s Karat which signifies purity). This simply denotes a measuring scale where each 1 carat = 0.2 grams (0.50 carat = 0.1 gram and 5 carats = 1 gram).

As the carat weight increases, so does the size of a diamond. However, confusingly, this relationship is not a linear but rather a curve - so a 2.0ct diamond will not appear twice as big as a 1.0ct diamond as shown below.

Expert Tip 1
When comparing similar diamonds, try to look at the measurements. Some diamonds with similar weights can vary significantly in measurements. Pick the one with wider measurements, and you will gain a larger diamond surface area for the same value.
Expert Tip 2
Certain diamond sizes are highly sought after (e.g. 0.50ct, 0.75ct, 1.0ct) and prices can vary dramatically depending on the carat weight. A 0.90ct diamond can be 10-20% better value than a 1.0ct diamond of the same quality but can appear almost identical in size but very different in price.


The term carat originates from the Greek and Arabic names for the carob tree - Keration in Greek and Qirrat in Arabic. The dried seeds of the Carob (or Locust) tree were once widely used by trading merchants as counterweights for weighing gold, diamonds, gemstones and pearls due to their relatively consistent weight and size. It is important to note however, that the term “carat” with reference diamonds is different to “karat” which is the value used for the purity of gold.
The Byzantine era used glass pebbles, based on carob seeds, for weighing coins, which weighed in at 196 mg, consistent with the average weight of an individual carob seed. However their use eventually diminished as it was discovered that despite their visual uniformity, the seeds were not actually consistent in weight. Many attempts were made to standardise the measurement of gemstone weight and it was only in 1907, at the Fourth General Conference on Weights and Measures that the “carat” was adopted as the official metric measurement for gemstone weights.
In 1913 the United States officially accepted the ‘carat’ as the gemstone measurement, and in 1914 the United Kingdom and Europe followed suit. By the 1930s, the majority of the diamond and gemstone industry had agreed to the standardised measurement, which is still in use today.
Dimensions play an important role in the appearance of a diamond. In addition to the carat weight, the distance across the top of the diamond must also be taken into consideration. A common misconception is that half a carat is half the size of one carat. In fact, a half carat is half the weight of one carat, but the millimetre difference on a round stone is only 1.35mm. The average measurement for a 0.50ct stone is 5.00mm, while the average 1.00ct stone measures at 6.35mm.
While carat weight may indicate a diamond’s size, the shape and cut of a stone also play a large part in determining how large or small the stone appears. An elongated shape such as the Marquise cut may appear larger than a rounded shape such as the round brilliant even if the two stones share the same weight. When comparing two stones of the same shape however, it is important to look at the cut grades and table and depth percentages, as shallower stones will tend to appear larger than deeper ones. Other aspects such as girdle width can also affect how large a stone appears, while not necessarily affecting the quality of the stone.

2. Cut

Far more than simply what shape a rough diamond has been polished into, the cut is the most important determiner of a diamond’s brilliance and light dispersion. Diamond cutting is an art requiring meticulous precision, and knowing how it all works is essential to making the right choice.

Often confused with a diamond shape, the cut is actually the grading that determines how well the diamond sparkles. It encapsulates Brightness (white light reflecting from the top surface), Fire (flares of colour) and Scintillation (flashes of light).

The cut grading currently only applies to Round diamonds as they are technically easier to measure in terms of light performance. Other shapes – such as Princess cuts, Cushions cuts, Emerald shapes, do not have a cut grading on their certificate but 77 Diamonds provide an estimated cut grading based on equivalent parameters.
Cut grades range from Excellent, Very Good, Good, Fair and Poor. The grading takes into account various attributes of the diamond that cannot be seen or measured with the untrained eye. An excellent cut grading will have the best light performance, mainly influenced by the relationship of surface table and the depth of the diamond (not too deep or too shallow).

Expert Tip
It is very hard to see the difference between an Excellent and a Very Good cut diamond as the direction of light is the same in both cut gradings. We therefore recommend you try to stick with an Excellent or Very Good cut, but if needed to fit the budget, a Good cut can offer an excellent-value alternative without any major compromises. Just make sure you are not on the "Deep" side or you will end up with a diamond that looks smaller than the actual carat weight.

3. Grade

Colour D

D is the highest colour grade attributed to a diamond, denoting that the stone is completely colourless (white); as such, they are extremely rare and command the highest prices.

Colour E

The colour difference between a D and an E graded stone is usually only visible to an expert gemmologist using master stones as a comparison, although E graded stones are slightly cheaper.

Colour F

The colour difference between an E and an F is only visible to an expert gemmologist using master stones as a comparison. F grades are the lowest and therefore least expensive of the premium colours.

Colour G

G graded diamonds are nearly colourless and a slight colour difference only become perceptible when compared to diamonds of grades D or E. G stones appear colourless especially once set and therefore offer excellent value for money.

Colour H

H coloured diamonds are near colourless diamonds which still appear totally white or colourless if they are not compared side by side with higher colour graded stones. The H colour is generally considered the watershed between colourless diamonds and slightly tinted diamonds.

Colour I

I coloured diamonds are very slightly tinted diamonds, however, once set in jewellery, these stones may appear colourless. If you are looking to maximize your budget, then an Icoloured diamond offers great value for money.

Colour J

J coloured diamonds are very slightly tinted diamonds, however, once set in jewellery, especially in yellow gold, it is harder to see the slight yellow tint which the J grade produces.

Colour K

K coloured diamonds are slightly tinted diamonds, however, once set in jewellery, especially in yellow gold, it is harder to see the slight yellow tint which the K grade produces.

Colour L

Seventy Seven Diamonds currently offers only stones in the higher range of D-J, as these are the only grades we recommend, however, lower clarity grades can be made available on special request.

4. Clarity

Almost all diamonds have small impurities or “inclusions” but they are not always visible to the naked eye. The size and location of the inclusions play a significant role in determining the price of a diamond so it is important to understand clarity grades in order to make the most suitable choice.

When diamonds are formed, deep underground and under extreme pressure and heat, imperfections in the crystal structure can form and mineral impurities become trapped inside the stone.

The size of these impurities and imperfections determine the clarity grading of a diamond. Diamonds without such impurities are very rare.
The grading scale starts from Flawless / Internally Flawless (FL/IF), Very Very Slightly Included (VVS1/VVS2), Very Slightly Included (VS1/VS2), Slightly Included (SI1/SI2) to Included (I1, I2 and I3). 77 Diamonds does not sell diamonds below SI2 as they are not considered suitable for jewellery. Generally, diamonds below a VS2 grading are likely to have visible inclusions to the naked eye however this is on a stone by stone basis.


Internationally Flawless: These rare high clarity diamonds are 100% flawless inside the diamond with no blemishes or inclusions.


Very Very Slightly Included 1: There will be one minor inclusion within a diamond of this grade but only visible under 20x magnification or more.


Very Very Slightly Included 2: There will be minor inclusions within a diamond of this grade but only visible under 20x magnification or more.


Very Slightly Included 1: Diamonds of this clarity will have several inclusions that are only visible with magnification of 10x but remain clean to the naked eye.


Very Slightly Included 2: Diamonds of this clarity will have several groups of inclusion that are only visible with magnification of 10x. A small percentage of these are not eye clean.


Slightly Included 1: Only 50% of diamonds of this clarity have no visible inclusions so it is important your selected diamond is eye clean.


Slightly Included : 85% of diamonds of this clarity have some form of visible inclusion or blemish to the naked eye.


Included 1: Due to the high level of inclusions here, we do not recommended this clarity grade for diamond jewellery.

Expert tip 1

As magnification is needed to see impurities in diamonds witha VS1 grading or higher, a choice of VS1 or higher is a subjective quality choice which goes beyond what can be seen to the unaided eye. Larger Diamonds with these higher grades are much rarer and therefore command greater pricing premiums, and also tend to perform better as an investment.

Expert tip 2

Although SI1 and SI2 are in general not eye clean, the impurities may be light in colour or scattered and so in up to 20% of cases, SI1 graded diamonds may appear to be eye clean. That number falls to just 5% for SI2s. There are many different types of impurities, but feathers and crystals are the most common forms of inclusions found in diamonds.

5. Certification

Diamond certificates are issued to confirm a stone's technical characteristics, value and identity, but it is important to know and understand the differences between the grading bodies as they operate on difference standards.

Ensuring your diamond is certified by one of the leading independent and recognised certification laboratories is essential for an unbiased assessment of the stone's quality. GIA, AGS, HRD, IGI & EGL are the leading grading bodies in the diamond industry, and are listed here in order of strictness. Today, expect most diamonds over 0.20ct to be graded by one of these.

Expert tip 1
As subtle differences in diamonds can have a massive impact on price, if you are offered self-certification or certifications from less stringent local grading bodies, it is generally because the seller can improve their margins by doing so. Please remember the comparison of such diamonds would NOT be like for like. Always demand a recognised international certificate to create a level playing field.
Expert tip 2
Even amongst the 5 internationally recognised certificates, there are differences. In fact, the diamond industry benchmarks every diamond against the GIA’s (Gemological Institute of America) strict standards. Comparing a diamond with a GIA certificate against an IGI or the weaker EGL is not an equal comparison. So like-for-like colours or clarity grading on EGL would be graded 2/3 grades lower if sent to GIA and therefore should reflect lower prices.

Laser Inscription

The 5 leading diamond certification organisations issue a unique number for every diamond, to protect the consumer. On most new GIA certificates and selectively on some other certificates, this number is laser inscribed in the diamond’s girdle, and can be easily verified with a magnification loop. This assures you the diamond you are buying is the actual one.

GIA Certificate & Laser Inscription

6. Contour (shape)

Elegant or eccentric, sparkly or subtle? From the ever popular round brilliant to the more unusual Marquise cut, diamonds come in all shapes and sizes and there is sure to be one to suit every taste and style.

It is often said that diamonds are a girl’s best friend, but perhaps less often pointed out that there is one to suit each and every kind of "girl". Every diamond has its own story and it is up to you which one you will choose to tell yours.
From the classic and versatile round brilliant which accounts for more than half of all diamonds sold today, to the more unusual and eccentric Marquise cut which harkens back to the glory of the age d’or, choosing a diamond can be as elaborate a task as choosing the man who will give one to you. For a change though, it’s not about who but what you know, and what you know about diamond shapes can help you through one of the most significant decisions you will ever make.
Beyond the fact that each shape specifically caters to an individual or personal taste, each one is also meticulously and mathematically cut to highlight a diamond’s best features, and which girl wouldn’t want all the best for her best friend?


Round Brilliant

Clean, classic, versatile and with more fire and brilliance than any other shape, it would be difficult to persuade anyone against this choice—as proven by the fact that it accounts for more than half of all diamonds sold today. (For men wishing to surprise their ladies and unsure of what they might like, one could hardly go wrong here).


Much like the round brilliant, the Princess cut is a classic and elegant shape, although with its sharp corners boasts more of a contemporary edge. This shape is ideal way to capture the brilliance and simple elegance of the round and still be "à la mode".


Speaking volumes of vintage glamour and old world charm, and favoured by such style icons as Grace Kelly and Jackie O, the emerald cut was one of the first cuts to be used in jewellery design, and with its broad flat plane highlights the clarity and natural crystalline growth of a diamond to unparalleled measure.


Replete with timeless elegance and Art-Deco cool, the Asscher cut is a rectangular shape similar to the more well-known emerald cut, with prismatic brilliance, tremendous lustre and a fascinating optical illusion known as the "Hall of Mirrors" effect.


Infamously given to Elizabeth Taylor by two-time-husband Richard Burton, the pear, or teardrop as it is sometimes called, is a unique and feminine shape with one rounded and one pointed end that makes for a delicate and stunning choice.


A square- or rectangular-shaped hybrid cut that combines thebrilliance and depth of the round, emerald and princess cuts, the radiant is the most brilliant of all the squared shapes making it both a beautiful and dramatic choice.


Somewhere in between the round brilliant and the pear shape,the oval cut is the perfect choice if you’re wishing to savour the sparkle of the round brilliant in a slightly rarer and more elongated form.


As its name suggests, the cushion cut is a square or rectangular shape with rounded corners, resembling a pillow shape. One of the rarer and more unique choices, the cushion cut’s large facets allow for great light dispersion, giving birth to a much larger range of spectral colours and making for a highly scintillating stone.


Originally commissioned in 18th century Paris by King Louis XV to emulate the smile of his mistress the Marchioness Madame de Pompadour, the Marquise harkens back to the glory of the age d’or, and is also an ideal way to optimise carat weight and elongate the finger.


Though most often used for a side or accent stone, with its stunning brilliance and fire, this triangular cut could make for a bold and dramatic solitaire, and has been increasingly appreciated for its impressive effect as a center stone.

7. Cost

There are various factors that affect the pricing of a diamond and a perfect balance of these will ensure you get the ideal diamond for your price range.

Diamond Costs

Our final C is often the first thing that is thought about when looking at purchasing any form of diamond... Cost. Across the various specifications for diamonds you will see that there are ways in which you can get the best value for your budget. You need not get the highest quality to get something that is equally as beautiful for your desired diamond.
Understanding the factors that influence price and what they are in reality is essential and allows you to make the best informed decision about what criteria offer the right compromise for your budget, setting your own personal levels of compromise within the scales. While the choice of diamonds may at first glance appear overwhelming and while there are many more specifications that can be taken into account the choices needn't be perplexing – and remember, ultimately, you're buying something that is a great vessel of value, and can be passed along for many generations.
Understanding the factors that influence price and what they are in reality is essential and allows you to make the best informed decision about what criteria offer the right compromise for your budget, setting your own personal levels of compromise within the scales. While the choice of diamonds may at first glance appear overwhelming and while there are many more specifications that can be taken into account the choices needn't be perplexing – and remember, ultimately, you're buying something that is a great vessel of value, and can be passed along for many generations.


Carat weight is one of the fundamental factors in determining the price of a diamond. As a general rule, the heavier the diamond, that is, the larger the carat weight, the more expensive it becomes. Price per carat is one of the best ways to compare the cost of similardiamonds. To calculate this, simply divide the cost of each stone by its carat weight. Because they are more scarce, larger diamonds are in much higher demand than smaller stones and therefore command much higher prices per carat. A diamond that is double the size of another can be up to four times the price. For example, a one carat diamond solitaire ring is nearly always more expensive than a diamond ring made up of smaller multiple diamonds whose total weight is one carat.

Undersize and oversized diamonds

Diamonds are usually cut to a rounded number in their carat weight, for example 0.70ct or 1.00 carat, rather than 0.69 or 0.99. Because of this, diamonds weighing just under the weight ‘barrier’ (e.g. 0.68ct or 0.69ct.), are scarce but highly recommended as they cost less than diamonds whose weight has been rounded up. Similarly, diamonds whose weight slightly exceed the barrier are referred to as “oversized” and also offer great value for money as they have not been rounded up.

Further Education

Ethical Diamonds

What is a conflict diamond?

When it comes to judging a diamond's quality, colour, cut, clarity and carat have always been used as the four cornerstones of evaluation, but in the last few decades, another essential 'C' has entered the vocabulary of gem specialists and consumers alike: conflict.
Conflict diamonds, which are also known as blood or war diamonds, are diamonds that originate from war zones and are illegally traded to fund rebel fighters and insurgencies. The name 'conflict diamond' is used to indicate that the trade of these diamonds funds — and ultimately, prolongs — conflict in war-torn countries.
Conflict diamonds are mainly associated with Africa, as insurgent groups in countries such as Angola, Liberia, Sierra Leone, The Democratic Republic of Congo and Cote d'Ivoire (Ivory Coast) have all sold diamonds in the past to pay for weapons and continue fighting. Not only do conflict diamonds perpetuate war and violence, but the treatment of workers in the conflict diamond industry is often reported as being inhumane, and rife with disease, violence and starvation. For these reasons, both the buying and selling of conflict diamonds is illegal.

How can you avoid buying a conflict diamond?

In 2000, the diamond industry established a process to prevent the circulation of conflict diamonds. This initiative, which is called the Kimberly Process, aims to track every diamond from the place it was mined to the place it is sold, thus preventing illegal conflict diamonds from being sold on the precious gem market. It is estimated that 99.8 per cent of diamonds on the market are now conflict-free, but you should still shop exclusively with retailers that are registered with the Kimberley Process Certification Scheme and that comply with industry standards.
If you ever feel uncertain about a company's credibility or the origins of the diamonds they are selling, then ask to see evidence of their Kimberley Process accreditation. All good retailers will be happy to do this, and if they're not, then look elsewhere to make your purchase.

How do 77 Diamonds comply with these policies?

Utilising the Kimberley Process and in compliance with the United Nations Resolutions, we only source our diamonds from legitimate sources that we know are not involved in any funding conflicts.
We guarantee that all our diamonds are conflict free based on written guarantees and personal knowledge from within the diamond industry.
We can therefore ensure that the diamonds you choose to be set in our jewellery are not from any area of conflict and we support the peaceful resolution of any existing conflict in war-torn countries.

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