With over 40 years of expertise in diamonds, we speak to people every day who are navigating the complicated task of buying a diamond engagement ring. It’s one of the most important purchases you will ever make and we understand that you’ll want to do all the research you can and feel as confident as possible in the choice you are making.


One of the questions we regularly get asked is “What’s the difference between a certified and a non-certified diamond and which should I buy?” So, we have decided to talk about this topic here on the blog. We’ll be explaining what certified and non-certified diamonds are and discussing the pros and cons of both.



Certified diamonds have had their quality verified by an independent, respected gemological laboratory. A certified diamond has been through a grading process. It has been judged on these four factors:


We often think cut refers to a diamond’s shape (round, oval, cushion etc.), but it actually refers to how well a diamond has been cut, its proportions and therefore how much it sparkles.

A well-cut diamond will give the best return of light, appearing fiery and radiant. If a diamond is poorly cut, it may appear dull and lifeless (even if it has good clarity and colour grades).

Out of the 4Cs, cut is the most important factor to consider as it is this that has the biggest impact on sparkle.

GIa Cut Scale


Diamonds are graded for their lack of colour. The whiter and more colourless a diamond is, the more valuable we consider it to be. The best colour grade available is ‘D’ (an ‘Exceptional White +’ diamond). As the grades progress through to ‘Z’, more and more of a yellow tint will be seen. This is due to the natural presence of nitrogen in a diamond when it is formed.

This presence of yellow is not to be confused with ‘Fancy Diamonds’ – a term used for diamonds with a distinct colour (yellow, blue and pink to name a few). Fancy coloured diamonds have their own grading scale and are valued for their depth of colour rather than their lack of colour.

To avoid a tint of yellow when buying a diamond, we suggest looking at colour grades of ‘G’ or higher.

GIA Colour Grading Scale


The clarity grade takes into account the number of inclusions that may be visible within a diamond. Clarity is graded on a scale of ‘flawless’ to ‘imperfect’. Inclusions can be seen with the use of a 10x magnification lens known as a jeweller’s loupe.

Inclusions can either be described as internal or external characteristics. These are natural flaws that form during the stone’s creation over millions of years. The most common type of inclusion can be seen as little black dots (the presence of carbon).

Clarity Chart
We suggest choosing a diamond that is ‘Eye-Clean’ and graded SI1 or higher. Diamonds with this grade have slight inclusions which are not visible to the naked eye.

For many people, it makes sense to buy a diamond with a small number of inclusions, as the stone will still be beautiful and appealing, but will cost significantly less.


When talking about carat, we are referring to the weight of a stone rather than its dimensions (size). Two diamonds with the same carat weight can have very different values (and prices) depending on the three other Cs: Clarity, Colour, and Cut.

The name ‘carat’ derives from the Latin name for the carob tree (Ceratonia Siliqua) as its seeds dry to a consistent weight of around 1/5 gram and were therefore once used by traders as a unit of weight for gemstones.

Carat is denoted by ‘CT’: 1ct = 0.2 gram 5ct = 1 gram

For intermediate measurements, each carat is split into 100 points: 1.00ct = 100 points, 0.50ct = 50 points, and 0.01 = 1 point

Engagement Rings On A Real Hand
To make the most of your budget, we suggest choosing a carat weight slightly below the whole and half-carat marks. You can expect to pay 20% more for a single diamond weighing in at 1 carat, as opposed to a stone of 0.95 carats. No-one will be able to notice the slight difference.

In the diamond industry, the cut, colour, clarity and carat of a diamond are known as ‘The Four C’s’. These Four C’s establish the overall quality of the stone. After the expert has completed the grading process, they will then accredit the diamond and give it a certificate.

If two diamonds with the same grade are sat side by side; one is certified and the other is not certified, the certified diamond will command a higher price due to the cost of certification.



Independent gemological laboratories certify diamonds. The laboratories serve as an unbiased authority and are not directly involved in selling and buying diamonds. One of the most respected laboratories is the GIA (Gemological Institute of America).

Diamond grading labs follow strict guidelines when assessing a stone. They try to make the assessment as accurate as possible by requiring that each diamond is appraised by more than one grader.

GIA Diamond Certificate



There is a common misconception that non-certified diamonds are of lesser quality than certified diamonds. This is not the case though; they are created in exactly the same way. Many jewellers carry non-certified diamonds. They are simply stones that have not been put through formal lab grading.

It is tempting to buy non-certified diamonds as they are often cheaper than certified stones. Confidence in the quality of the diamond can be achieved by dealing with a reputable jeweller and talking to a diamond expert. A consultant can help by comparing non-certified diamonds with certified counterparts. The question we suggest you ask yourself is “can I see enough of a difference between this non-certified and certified diamond to warrant paying the extra money?”

A good sales consultant will also show you how to view the diamond with a loupe (a magnifying lens specifically for looking at gemstones), and point out the flaws if you can’t see them at first.



Buying a Diamond Ring In-Store

Buying a Diamond Ring In A Store

The Positives of Purchasing a Diamond In-Store

  • Buying a diamond can be overwhelming. With the guidance of an experienced professional, the process can feel more relaxed and comfortable. It can be reassuring to talk to an expert face to face about your requirements and any concerns or queries you may have.
  • You should never underestimate the importance of being able to physically touch and feel a product, especially if you are about to part with a significant amount of money.
  • Also, if you find your perfect diamond, you can walk away with it immediately rather than waiting for the postman to deliver it!

The Negatives of Purchasing a Diamond In-Store

There are not many disadvantages to buying a diamond in-store. One downside is that there may be a smaller selection of diamonds instantly available to you for comparison purposes. However, a further selection of loose diamonds could be sourced and sent in for viewing on another day.

Buying a Diamond Ring Online

Researching Online

The Positives of Purchasing a Diamond Online

  • The main reason someone would purchase a diamond online is, quite frankly, because it’s cheaper. This is because online companies have very few, if any, overheads.
  • Online companies have access to a range of diamonds all over the world. This makes it quicker to compare prices of varying qualities and carat weights.

The Negatives of Purchasing a Diamond Online

  • Comparing diamonds physically becomes quite tricky online, as they are sold by weight and not by the dimensions (size). For example, you could have two 0.75ct diamonds listed, but if the weight has been cut into the pavilion (bottom section) of one of the diamonds, it will look much smaller than the other.
  • Most of the images of diamonds online can be quite misleading as they have been taken in a lightbox and are blown up in proportion. This doesn’t best portray how the diamond will look in natural light when it is eventually worn.

Buying a diamond is a very emotional purchase, and so regardless of purchasing online or in-store, you should trust your own eyes and gut feeling. You want to have no regrets about this important purchase.



Because almost any diamond can be sent to a lab for certification, the mere fact that a diamond is certified does not mean that it is of superior quality. Just because a diamond has not been certified, this doesn’t mean it is any less desirable or low in quality.

Buying a certified diamond will give you peace of mind and with a guarantee of the quality, a better resale value is achieved.

However, if you are dealing with a reputable jeweller (who is well established), or if you are on a budget, then a non-certified diamond may be a great option for you.



We hope we have helped you further along your journey to finding the perfect diamond. If you have any more questions, we’d love to help you. You contact us here.

If you would like to view our collection of both certified and non-certified diamond engagement rings, we would be delighted to meet you in one of our stores. You can find your nearest one here. Or you can view our engagement rings online here.