Diamonds Buying Guide

At Ernest Jones, we understand that purchasing a diamond can be an emotional investment as well as a financial one. We have over 60 years of experience in delivering expertise in diamond jewellery, so you can trust and feel confident that you have come to the right jewellers. As part of the world's largest specialist jewellers, we will be able to go through the characteristics of each and every diamond and guide you in choosing the piece of diamond jewellery that is perfect for you. If you want that extra peace of mind, a certificated diamond is just the thing. Every certificated diamond comes complete with a Jewellery Identification Report from the International Gemmological Institute, an internationally recognised grading laboratory. Whether you are looking for more information on diamonds, or you are looking for a specific type of diamond jewellery, our diamond buying guide has everything you need to know.

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Our diamond sourcing policy

Is there anything more luxurious than diamonds? At Ernest Jones, we understand how important diamonds can be, whether it comes to finding the perfect diamond engagement ring or choosing the ultimate set of diamond earrings to complete your look. We also understand the need to irradicate unethical diamond sourcing practices from the industry.

Our diamond sourcing promise

We are passionate about our customers and the products we sell, to this end, our promise to you is that the jewellery you buy is sourced responsibly and backed with strong measures in place to monitor the social, environmental, and ethical aspects of our entire supply chain. We are dedicated to the continuous improvement in the integrity of the global jewellery supply chain as such, we continue to lead the industry in responsible sourcing. We do this, not only because it meets the expectations of our customers and employees, but also because it is the right thing to do.

3 Rings Gold Silver and Platinum

Conflict-free diamond sourcing

As diamond experts, we like to lead by example. We collaborated with industry partners in the supply chain to advance rigorous sourcing standards through the Signet Responsible Sourcing Protocol (SRSP).

  • The SRSP is designed to ensure that our supply chain is free of any contribution to conflict or human rights abuses.
  • The SRSP was developed to establish a global, best-practice standard for our entire supply chain, comprising legal requirements, United Nations guiding principles, and a process of continuous improvement.
  • The SRSP goes beyond the legal requirements, implementing best-practice standards for supply chain due diligence.

The Diamond 4 Cs

A diamond’s value is predominantly determined by 4 factors, commonly known as the 4 Cs. These include colour, clarity, carat and cut. When purchasing diamond jewellery, it is important to understand why two diamonds that look the same to the naked eye may differ significantly in terms of value. Before buying a diamond ring or jewellery, the following section will help you understand the 4 Cs in more detail:

Diamond Colour

Diamonds naturally vary in colour, with the majority on the market being sold as near colourless. At Ernest Jones, we use the GIA (Gemmological Institute of America) scale of colour. On this scale, diamond colour is graded from D, which has the least colour, through the alphabet to Z, which has a light yellow colour. Truly colourless diamonds (D) are treasured for their rarity.

At Ernest Jones, we have a wide range of coloured diamonds including black diamonds, which are natural diamonds that have been subjected to specialist treatments to enhance the depth of colour and contrast.

Diamond cut

The cut of a diamond refers to their proportion and finish and shouldn’t be confused with the finishing shape of the diamond. Skilled craftsmen transform a rough diamond to a gleaming polished diamond by polishing tiny facets into the rough stone. Facets are the flat, polished surfaces on a diamond. Well cut and proportioned facets on a diamond will make good use of light, allowing it to be dispersed and reflected from one facet to another, releasing the diamond’s brilliance. Symmetry, proportion and how the diamond is polished will all determine the quality of the cut.

Diamond Carat

Diamonds are also graded by carat, which refers to the weight, rather than the size of the diamond. Carats are split into points, where 100 points are equal to one carat.

½ carat diamond – 50 point or 0.50 carat diamond

¼ carat diamond – 25 point or 0.25 carat diamond

When there is more than one diamond on a piece of jewellery such as on a diamond cluster ring or a three-stone pendant, the stones are weighed together rather than individually. The carat weight does not reflect the size of a diamond.

When buying diamond jewellery, the most appealing factor is likely to be the carat weight of a diamond. However, it is important to remember that the cut will also determine the value of a diamond.

Diamond Clarity

Diamonds naturally vary in colour, with the majority on the market being sold asnear colourless. At Ernest Jones, we use the GIA (GemmologicalInstitute of America) scale of colour. On this scale, diamond colour is graded from D, which has the least colour, through the alphabet to Z,which has a light yellow colour. Truly colourless diamonds (D) are treasured for their rarity.

Diamond Shapes

baguette diamond ring


This slim and rectangular-shaped diamond is the most familiar form of step cut. A popular choice for eternity and wedding rings, they are also used as an accent stone to accentuate a larger stone in a diamond cluster ring or are united with similar sized round brilliant cut diamonds to create a stunning look.

brilliant round pendant

Brilliant Round

For the traditional bride, a round brilliant cut is a popular option for an engagement ring. The stone is cut in the shape of a cone with the top rounded off which enables it to return the light that enters it. It is considered the most brilliant of diamond cuts as its symmetrical shape allows it to maximise all its qualities.

cushion cut


Over the last 100 years, the cushion cut diamond has gained popularity because of its rounded corners and larger facets for enhanced brilliance. Also known as pillow cut diamonds; they can be square or rectangular in shape.

marquise cut


As its name implies, this method of cutting was originally used for the cutting of emeralds, The emerald cut diamond is designed to draw attention to a diamond's shine. An emerald cut diamond has a rectangular top with chiselled corners. This shape is enjoying a huge revival in diamond jewellery.

marquise cut


Folklore would say the marquise shape was created at the request of King Louis X1V who wanted a stone to represent the sultry smile of his mistress, the Marquise de Pompadour. Marquise diamonds work beautifully as a central stone in a diamond engagement ring, or as an accent stone in diamond jewellery.

oval cut


An oval diamond engagement ring is perfect for the woman who adores the fire of the round brilliant diamond, but wants something slightly different. The oval shape was designed in the 1960s by Lazare Kaplan, the cousin of Marcel Tolkowsky who aided the development of brilliant round diamonds.

pear cut pendant


This unique diamond which is also known as a teardrop because of its single point and rounded end exudes simple sophistication. The pear-shaped diamond is a brilliant-cut diamond that blends the shape of an oval diamond and a marquise diamond.

princess cut earrings


Created in the 1970s, this modern style is an adaptation of the standard brilliant cut which highlights the diamond's fire. The top of a princess cut diamond is square with pointed corners, while its general shape is a pyramid. Radiating fire and brilliance, princess cut diamond engagement rings are a contemporary alternative to the classics.

radiant cut rings


Developed in the 1970s by World War II veteran Henry Gossbard, radiant cut diamonds unify the grace of an emerald cut diamond with the brilliance of a round diamond. This is a versatile choice for diamond jewellery as it has trimmed corners and 70 facets giving it an individual look.

Build your diamond jewellery collection

Throughout history, diamonds have been the most highly valued of gemstones, worn and admired by royalty as a symbol of strength and status. Over the centuries, diamonds have also become the ultimate declaration of love in the form of engagement rings, eternity rings and contemporary wedding bands.

Diamonds possess a unique character, elegance and remain simply timeless, making them a great choice of gemstone for any piece of jewellery. Here at Ernest Jones, we have a wide collection of stunning and unique diamond jewellery, varying in colour, cuts and sizes, allowing you to create a fashion-forward statement, whatever your style.

How to choose diamond jewellery

Deciding what style your special someone would prefer can be difficult, but here are a couple of factors you may wish to consider:

What style?

Glamorous, vintage, minimalist or contemporary? An easy way to find out is to discreetly search through her current jewellery. If it is oversized and decorative then she may prefer one of our diamond halo cluster rings. If her jewellery is more refined and classic, she may prefer one of our diamond solitaires or three stone diamond rings.

What metal?

Perhaps take her past an Ernest Jones store to see which one she points to more or take note of what colour jewellery she currently wears.

Classic or unique?

With the rising trend of rose gold, perhaps a rose gold diamond engagement ring would make a great choice. Or if she is a lady who loves a dash of colour, perhaps she would fall in love with one of our coloured diamond engagement rings.

Keep it classic

Let’s take a look at some of the different types of diamond jewellery…

diamond rings

Diamonds Rings

Diamond dress and cocktail rings can add glamour to any outfit and make treasured gifts for birthdays, Christmas or simply as a treat for yourself.

For a pop of colour, dress rings and cocktail ring combined with coloured gemstones are a great way to personalise your style.

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diamond necklaces

Diamond necklaces

Whether you're looking for minimalist chic such as a diamond solitaire pendant, or perhaps statement style with a diamond cluster necklace.

At Ernest Jones we have a wide collection of diamond pendants and necklaces for you to choose from that will add sparkle to any outfit.

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diamond rings

Diamond Earrings

For sparkling glamour, diamond earrings should be a staple accessory in every woman's jewellery box. They add a touch of elegance to any outfit.

Try a classic diamond stud or diamond drop earrings for the contemporary look. View our full diamond earrings collection

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diamond bracelets

Diamond Bracelets

Get timeless sophistication with an elegant and classic diamond tennis bracelet.

An attention-grabbing piece of jewellery that ranges from modern and chic to decorative and exquisite styles. View our full diamond bracelets collection.

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Shop diamonds

At Ernest Jones, we offer a range of services to guarantee that you are confident with your diamond purchase. Your diamond is secured against any flaws in craftsmanship for 10 years. If you have a Diamond Privilege Card, we will give you a lifetime promise to clean and inspect your diamond engagement ring annually for free at any Ernest Jones store.

Shop instore

Want a more intimate and personal experience? Why not find your nearest Ernest Jones with our handy store locator and shop instore. Need advice on diamond jewellery? Book a one to one consultation with one of our experts. Our knowledgeable team will be able to assist with any purchases or answer any questions you may have.

Shop diamonds with Ernest Jones

Ready to make that all important purchase? You can find everything you need here in the Ernest Jones online store. Not sure exactly where to start? Head over to our diamonds page for a little inspiration. Already know exactly what you want? Create your dream ring now using our "create your own" section. Start designing your own ring.

Interest-free credit

Got your eye on the perfect diamond piece but worried it may be a little out of budget? Why not consider finance on your dream jewellery? With 0% APR for up to 3 years, you can spread the cost over time and enjoy your jewellery immediately. Find out more on our finance page.