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Article: Essential guide on choosing diamonds & buying the perfect engagement ring

Essential guide on choosing diamonds & buying the perfect engagement ring

Essential guide on choosing diamonds & buying the perfect engagement ring

Buying a diamond is not an easy task and can be quite daunting for those who are new to this endeavour, especially if the stone is to commemorate something as significant as an engagement! So before you go ahead and make that all-important purchase, it’s good to have some prior understanding about diamonds and how to choose the one that is right for you.

With over 30 years of experience in the industry, as a qualified gemmologist and independent jeweller, Louise is passionate about diamonds and coloured stones. It’s important to her that her clients enjoy the process of designing their own bespoke piece without getting stressed or overwhelmed. Continue reading to discover Louise’s main points to consider when choosing diamonds or buying that perfect engagement ring and you won’t go wrong!

So without further ado, let’s get started!

How to choose a diamond

1. Know your 4C’s: Cut, Carat, Colour & Clarity
In the industry, the 4C’s are considered to be the four most important characteristics in determining a diamond’s value and look. Striking the delicate balance between these four as well as budget is essential to ensure you end up with the perfect stone within your price range. When working closely with you on your piece, Louise will guide you every step of the way, advising and informing you about your options and addressing any questions you may have.

The cut is often considered to be the most important one of the 4C’s and although as the name would suggest, it does not refer to its shape but rather the way in which it was cut. This one of the 4C’s is so essential because it determines the geometric proportions of the stone and therefore the diamond’s brilliance and how it shines. A well-cut stone will refract light back out to the observer’s eye, giving it that all mesmerising sparkle which makes diamonds so desirable. The art of cutting a diamond is highly technical, and it takes a very skilled jeweller to be able to cut a stone so that its symmetry and proportions achieve maximum light dispersion.

The carat of a diamond refers to its physical weight, whereby 1 carat equals 0.2 grams. The higher the carat, the more it weighs and hence the higher the price tag. It is also worth noting that larger diamonds have a higher value per carat as they are more rare than smaller ones. Carat is also not to be confused with the karat in which gold is measured.

Diamonds are graded from a scale of D (colourless) to Z (light yellow) and the less colour it has, the more valuable it is as colour inhibits the stone from refracting light in a spectrum of hues, giving that alluring sparkle. Genuinely colourless diamonds (graded D to F) are very rare, therefore highly desirable but also more costly. Louise does not sell diamonds less than Grade H in colour as her clientele has come to trust and rely on her to only source the highest grade stones.


The clarity of a diamond refers to the naturally occurring inclusions or blemishes the stone possesses, which make every stone unique. Clarity is measured in 11 grades on a scale from IF (Internally Flawless) to I3 (Included Grade 3). The fewer inclusions, the higher the clarity and therefore the more exceptional and valuable it is. Stones sourced by Louise do not go below VS2 clarity.

To summarise, the 4C’s play a vital role when it comes to choosing diamonds. Ideally, we would love to chose the highest grade for each C, however as that is in most cases not possible due to budget constraints, adjusting each of the characteristics in line with your preferences and price range to strike the ideal balance is essential. Depending on which ones are more important to you in the purchase of your perfect stone, you may place preference on the colour over the cut, or perhaps you are willing to go for a lower cut in exchange for higher clarity.

2. Choose your diamond shape
A skilled craftsman will cut a diamond with the fewest flaws, the biggest size and highest brilliance. The round solitaire shaped diamond is one most people are familiar with. However, there are various other more elaborate shapes available. This is all a matter of personal taste so choose wisely what you think is best suited to you, or for the person you are buying for.

You may notice that fancy cut diamonds are at a premium price point in comparison to round brilliants. This is because not only do they lose more ‘weight’ during the cutting process of the rough stone, but they also need to be of better colour and clarity to be suitable for a fancy shape, hence reflected in the cost.

Our below chart displays some of the most common shapes.

3. Consider polish, symmetry and fluorescence in line with budget and size
A diamond’s finish in a grading report is characterised by its symmetry and polish. The condition and smoothness of the stone’s surface are determined by the cutter’s polishing skills. Except for flawless stones, all diamonds will have even the minutest of polishing marks on their surface, although not visible to the naked eye. The most important factor is that the marks are no deeper than surface level, which would be the case with naturally occurring imperfections impacting the stones’ clarity.

Symmetry, on the other hand, can be either facet or proportion related. A proportioning flaw relates to the balance of a stone’s facet structure as well as its alignment. Facet related flaws indicate the irregularity of the cut of individual facets within the stone. One thing to note is that a cutter may sacrifice symmetry to avoid inclusions or retain weight when crafting the stone as that will retain more of its value.

Both polish and symmetry are rated on a scale from Excellent to Poor and Louise recommends opting for Excellent or Very Good stones.

Fluorescence is often a debated topic and refers to the glow emitted by the diamond when subjected to UV light. Although studies suggest that fluorescence makes very little difference to the appearance of a stone, it may be something you wish to consider when choosing your perfect one. Louise can advise you further on this aspect during the design process.

When shopping on a budget, it is good to understand where you can sacrifice perfection and still get a beautiful diamond. Both symmetry and polish can affect the refraction of light and hence how much your diamond sparkles. We would recommend prioritising the polish as opposed to the symmetry, as it has a more direct impact on the brilliance of the diamond. Another thing worth mentioning is that with the more fancy shaped diamonds, it is almost impossible to attain perfect symmetry, as they naturally lack a specific structure.

4. Make sure you obtain a diamond grading report
If your stone’s weight is anything over half a carat, insist on having it certified by a reputable board such as the GIA, HRD, EGL or IGI. The certificate includes the diamond’s details such as the 4C’s and precisely states all characteristics of the stone. A certificate also serves the purpose of verifying the identity and value of a stone, essentially acting as a ‘passport’ so to speak.

With direct access to international bourses and stockholders worldwide, Louise only buys diamonds which are already GIA certified, due to the body’s international recognition. You can also be sure that all stones have the appropriate paperwork, so you know exactly what you are buying!

Buying the perfect engagement ring

So now that you know about the basics about choosing diamonds, here are some additional things to consider when it comes to buying the perfect engagement ring; the one that will make her say YES!

5. Decide on your budget
Before choosing that all-important stone, you need to decide on your budget as that will determine other factors such as how extravagant you can be with the 4C’s and other characteristics. So be realistic but know you can still have a beautiful diamond within your budget.

6. Choose the setting
The way in which the stones are held in the setting of the ring is a key design element. Each setting creates a unique look and this, similarly to the shape of the stone, is a very individual choice determined by personal taste.

7. Coloured gemstone vs white diamond
Although ‘white’ or ‘colourless’ diamonds are the most popular and traditional choice to pop the question with, coloured-stone engagement rings boasting the likes of sapphires, rubies and emeralds are growing in popularity, especially amongst more modern and younger brides. There is an increasing trend and desire to own something unique with a bespoke design, as well as a piece that is expressive and vibrant. A famous example is Catherine, Duchess of Cambridge’s sapphire and diamond cluster ring, previously belonging to Lady Diana.

Coloured stones not only offer greater design diversity and individual expression, but they also have a more accessible price point in comparison to diamonds. As there is a vast array of options in terms of quality, cut and colour, couples can work closely with Louise to design an individual piece, which in the end is an amalgamation of both their creative visions. Quite a romantic sentiment!

Above: A platinum sapphire cushion and diamond ‘half moon’ shoulder stones in a claw setting—a bespoke commission made by Louise Sinclair.

8. Pick side stones
If you want a more elaborate design to the single-stoned ring, you can add side stones to complement the centre diamond. Things to consider would be: choosing matching diamonds that are within the same colour grade or two; alternatively, coloured diamonds as side stones really emphasise the centre stone; proportions of the stones in relation to the wearer’s hand; and last but not least, using different coloured metals for the centre and side stones to really make them stand out.

8. Pick a metal for the mount
Choosing a metal for the ring goes hand in with choosing the setting and as an engagement ring is supposed to be ‘for ever’, the chosen metal needs to be durable so that it can be worn for decades. Commonly, the metals of choice are 18 karat white, yellow or rose gold, or a combination of these, as well as platinum. Note that the metal colour will affect the appearance of the diamond.

9. Choose a ring that suits her style, not yours
One thing that is often forgotten is that you should choose an engagement ring that suits HER style and taste. After all, she is the one that will be wearing it every day for the rest of her life! Ask yourself these questions to narrow down on some of the design elements such as shape, setting and cut:

  • What kind of jewellery does she usually wear?
  • Does she prefer gold or silver?
  • Is her overall style more classic and understated or modern and bold?
  • Is her current jewellery simple or ornate? Chunky or delicate?
  • Is she more of an outdoorsy, active person or does she tend to dress fashionably and likes to make a statement through her jewellery?

10. Last but not least, know her ring size!
If you don’t already know, borrow one of her rings that she wears and trace along the inside of the ring with a pencil on a piece of paper. Alternatively, press it into a bar of soap to take an imprint or if all else fails, put it on one of your fingers and draw a line where the ring stops. 


As you can see, there are quite a few things to think about when choosing diamonds or buying an engagement ring. After all, you may be investing quite a bit of money, or more importantly, you may be about to take the plunge and ask her to marry you, so you definitely want peace of mind when it comes to your purchase.

With three decades of experience in this industry, Louise knows her trade inside out. Since her specialisation focuses on diamonds and coloured stones, you can trust that your final bespoke piece will be everything you had hoped it would be and more! She will work together with you from the very start of establishing what you are looking for, to sourcing your stone and finally handing you that exquisite finished product.

If you wish to discuss your requirements in detail, please contact Louise to book an appointment and start this exciting journey today!

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