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How To Choose A Diamond For An Engagement Ring

Imagine: You’ve done it. You’ve just proposed. And the answer was “Yes!”. Now imagine being able to confidently share intricate details of the stone that you have used to help declare your love. Wouldn’t that prove that the moment she has just experienced was so much more than a gesture; but rather an expression of consideration, care and confidence in its future? We all know the way that diamonds are created; hidden deep in the earth for millions of years, resisting immense pressures and geological forces before becoming beautiful precious gems. We know about the world’s hardest natural substance, And we know that diamonds symbolise love, security, dependability and eternity. But what about the 4 C’s: Cut, Clarity, Colour, Carat? What shape diamond should you choose? Learn about all of these – and more – and arm yourself with the knowledge of how to choose the perfect diamond for your engagement ring. Just imagine what an impact your proposal will have If you know the specific details of the diamond you choose for your engagement ring: if diamonds are a girl’s best friend, what does that make diamond experts?


There are dozens of elegant cuts of diamond which give tremendous variation in terms of design for rings and fine jewellery. Here are some of the most popular, and some of our lesser-known favourites.

An Emerald cut diamond has a subtle sophistication that imparts quality and taste – not too bright with few facets but as clear as crystal with a life of its own. We like to mount them across the finger (for average size stones) for a totally different look from the traditional up and down the finger look. This way round is also conducive to the wedding ring fit.

Princess cuts (really a square brilliant cut diamond) are full of fire and stunning on its own in a well presented four claw setting whilst by adding say a pair of trillion cut (triangular) shoulder diamonds a brilliant three stone ring is produced. Square Cut diamond engagement rings are only behind round brilliant cut in popularity. Due to the timeless, elegant style square cut stones fit seamlessly into a wide range of settings and equally suit being showcased in a solitaire ring, as part of a shoulder set or in two and three stone settings. This cut has rapidly increased in popularity as an elegant diamond shape. Admired for its streamlined angles, the Square cut makes a perfect diamond when looking for something extra special. With such stunning variety to behold within the Wharton Goldsmith Square cut range, we are confident that you’ll find the ideal ring to suit any taste or sense of style. Offering divine shimmer and sparkle, our square cut selection celebrates vintage and classic styles as well as intricate, more modern takes. Square cut refers to all diamond cuts with a square or rectangular shape and includes the popular Princess cut and Baguette cut.


A softer, square look can also be obtained with a cushion cut (overall square but with curved sides and corners). Adding tiny diamonds around the centre adds size and overall brilliance and for a real effect diamond in the shoulders and sides of the actual setting look impressive and unusual.

The invention of the Radiant cut back in 1977 (designed by Henry Grossbard) was a real breakthrough in terms of the resulting brilliance of the cut. Up until 1977 all square or step cut stones were much less brilliant, similar to a typical emerald or square cut diamond. Henry Grossbard’s idea was to create an elegant rectangular or square stone with cut corners that would rival the brilliant cut diamond for brilliance. His design had 70 facets and was an immediate success and is now in the top ten of diamond cuts. Famous Radiant cuts belong to Jennifer Lopez, a rare pink stone of 6.1cts, Khloe Kardashian with 12.5cts and Drew Barrymore’s 4cts.

The Marquise cut is generally less used than most of the other fancy cuts but mounted thoughtfully they can look superb. I have one particular design across the finger that clearly shows the clean simplicity of its form. Set into a simple cradle setting with open sides and strong V shape claws at each end which follow the shape of the stone.


Pear shape diamonds look beautiful as single stone pendants and earrings whilst as a ring in a curvy cross over style it gives a really different look.

Oval cut diamonds are one of my favourite cuts – not quite as bright as a brilliant cut but weight for weight are always bigger and they represent excellent value for money when looking for a large spread stone. The cutting style is soft and feminine and lends itself particularly to engagement rings. We have a number of beautiful oval cut designs in stock.

Lastly the Brilliant cut, the most popular cut of all time. With 58 facets and stunning light refractive qualities, it is truly the king of diamonds. It is the most versatile in the number of ways it can be mounted, larger stones for engagement rings, pendants, earrings, bracelets and the smaller stones used to create decorative shoulders for rings or intricate patterns on a bracelet. Its uses are endless.

For me a beautiful coloured diamond centre such as a vivid yellow diamond with a contrasting addition of high colour white diamonds makes a great contrast full of warmth and fire. Alternatively I also love a single stone diamond ring with a well presented One Carat D Colour Diamond in a simple but modern setting.

At Christopher Wharton Goldsmith we have one of the largest collections of diamond engagement rings anywhere in the UK with simple sophisticated and innovative design for all tastes. Never mediocre – always different.

The Quality Of A Diamond

Now we know about the various diamond shapes, let’s look at quality factors. The basic rules for judging the quality of a diamond are known as the Four C’s: Cut; Colour; Clarity; Carat. We’ll cover these main considerations, discuss Diamond Certification, and look at a few less-obvious quality considerations.


This term is often used incorrectly: “Cut” is not a description of the shape or style of the diamond. Cut refers to the quality of the cut including the precision of its angles and proportions. This has a huge effect on the ‘sparkle’ or light that is reflected. The cut of a diamond is graded from ‘Excellent’ through to ‘Poor’. The cut of the diamond is arguably the most important part of the creation of a beautiful stone. Unless it is cut with absolute precision it will not have the perfect proportions needed to produce maximum light and fire. Slightly too deep and it will lose light, have a smaller overall size (“spread”) and look heavy. Too shallow (too big a “spread” relative to its size) and it will also lose light, have a thin girdle, and often have an “open window” effect through the top of the stone. Exact ‘Ideal’ proportions mean maximum brilliance, fire and light coming up through the stone. Light performance is made up of 1. Brilliance (reflected white light) 2. Fire (refracted light or dispersion) and 3. Scintillation (sparkle).

The History of Diamond Cuts

Primitive diamond cutting began in the middle ages in Europe although the first diamonds to be rudimentally cut were in India a century earlier. The first was called the Point Cut which basically partially polished a rough diamond crystal. It was soon discovered that diamond dust could be used in tools to polish diamond and that started diamond cutting in earnest with the birth of the Rose Cut with a flat backed and dome top stone with 24 facets that gave off a soft diffused light. Quite different to a modern brilliant cut that has a culet and table. The Old Mine Cushion Cut came into existence in the 18th century in Europe. They were basically square or off-square with rounded sides and were really the forerunner of the brilliant cut diamond. It was only when ‘Bruting’ was invented that cutters were able to perfect a round cut stone from the natural form of the crystal. In 1919 Tolkowsky made public the ideal proportions of a diamond to give stones the lustre and brilliance that had never been seen before. It had 58 facets and was the forerunner of the modern Brilliant Cut which merely perfected his formula. Most of today’s modern cut diamonds are cut in India. They have 92% of the worldwide diamond market in numbers of stones produced.


The best quality are the colourless stones graded D Colour (exceptional white), which are referred to as “white diamonds”. At the other end of the colour scale is Z, which is heavily tinted. Colours D and E (Exceptional White) are graded as ‘colourless’ with F, G and H (Rare White) are near colourless. From colours I – M (Slightly Tinted), N – R (very light yellow) and S – Z (light yellow). The colour of a diamond is a major part of its character. Whilst an icy white D or E colour is pure and vibrant, a beautiful yellow colour can be warm, glowing and full of lustre. 


This is relates to flaws (aka “inclusions”) within the stone or surface blemishes. Flawless diamonds are naturally the most expensive because of their purity. Most cut diamonds have flaws which are also known as ‘inclusions’: tiny white crystals or small black carbon deposits which according to their size and intensity can directly affect the refraction of light through the diamond and consequently the value of the stone. At Christopher Wharton Goldsmith we only choose diamonds that are clean to the naked eye and even when inspected by 10 x magnification any inclusions are so small they can barely be seen. Clarity begins at ‘FL’ for Flawless, ‘IF’ for Internally Flawless. Then there is VVS1-VVS2 for Very Very Slight Inclusions, VS1-VS2 for Very Slightly Included (invisible to the naked eye) and SI1-SI2 for Inclusions only visible under 10x magnification. P1-P3 refer to diamonds with inclusions that are visible to the naked eye. If you go for an SI stone try to ensure you go for a white SI as opposed to the black SI which is often allot more visible to the naked eye. Also try to make sure the table is clean. This is what we call a “clever stone” in the trade. 


Carat is the way that diamonds are measured in terms of weight, and is further measured by points. There are 100 points in a carat. In general terms the higher the weight the more expensive they become. Diamond sizes of .30cts to 1 carat are the most popular. A smaller perfectly made stone of high colour and clarity can often stand out far more than a larger poorly made and off white stone. There are certain break points in the weight where the price will change and more will be charged per ct as the weight goes up. The break points are as follows. 0.25+ 0.30+ 0.40+ 0.50+ 0.70+ 0.90+1.00+ 1.50+ etc. You must also take into account there will be premiums for certain sizes like 0.60+ or 1.20+ on the same note you can also benefit by reducing the weight by a couple of points to take advantage of the lower price per ct for example instead of buying a 0.50+ go for a 0.48ct which is going to be very close in spread depending on the cut but at a significantly lower price.

Diamond Certification

Whilst a diamond certificate by a top laboratory is a very good guide to the characteristics of a diamond it is by no means the most important aspect of buying the stone. Every diamond is individual and unique and will display its own character regardless of its credentials on the certificate. Also bear in mind that not all certificates are the same. You cannot compare like for like on the diamond parameters when you have a different type of cert. This in certain instances can have a vast impact on the price. Don’t pay GIA Premiums on an EGL Cert. Also be aware of the different international laboratories within that particular governing body you are looking at. The results can be very different. At Christopher Wharton Goldsmith we will always show a selection of loose diamonds under white light and on a white background in order to clearly show our customers the clear and not so clear differences between each stone. 


Five Tips For Buying A Healthy Diamond

By now I’m sure you are starting to understand why it takes 15 years of training to be a diamond grader. Buying a loose diamond online or second-hand is a minefield for an untrained person – you should always see it in real life before you commit. Even if a diamond appears cheap there is almost always a reason. For example, there are ideal proportions that help a diamond give that wonderful “fire” or brilliance; however this is often sacrificed in order to shape a stone to make it look bigger. They may simply be poorly cut resulting in a dead looking stone. Cheaper stones may also be slightly dull or slightly milky. Diamonds can have a natural fluorescence which causes this.

Here are five more points you generally won’t get told when buying a diamond online, each point will have a significant bearing on the cost.

1. Lustre – This is closely related to colour, and I think of it as “milkyness” or “cloudiness”. Just be careful here Don’t pay the premium on a D E colour only to find out the actual material is milky looking. This is usually not documented on a certificate and can dramatically have an impact on the value of the diamond; this is known as the lustre. Generally this sort of material generally comes from Zimbabwe.

2. Symmetry – Really speaks for itself, another big factor that contributes to the diamonds value. The measurement is always a good tell tale sign there are always two measurements on a girdle diameter, just make sure there not too far apart.

3. Fluorescence – Reduces the value but has its benefits you will get noticed on the dance floor with those ultra violet lights. Can also have an effect on the appearance of the stone. Having said that slight/very slight is acceptable.

4. The Girdle – Often not talked about this is the edge round the circumference of the stone. Is it polished or not. An unpolished girdle will often cause the diamond to lose one colour at least. Also make sure it’s not too thick or thin. A thick girdle is ugly more than anything and a thin girdle will be prone to being chipped.

5. The Culet – Make sure it’s not chipped, often quite visible when looking at a diamond face up. Our Diamonds Chris and Sam Wharton source fine diamonds from proven legitimate sources all over the world.

We are totally committed to finding and supplying only the best possible stones for our customers. Please don’t hesitate to get in touch if you would like any further advice on how to choose the perfect diamond. In the meantime, you can explore our engagement rings by shape, gemstone and metal, or visit our At A Glance Style Guide to find the perfect engagement ring style.