Diamond Certification: Complete Guide

Developed by the Gemological Institute of America (GIA) in the 1950s, a diamond certification (also known as a grading report) is a universally accepted way of valuing a diamond by assessing its qualities. This process involves looking at the 4Cs: cut, colour, clarity, and carat — deep-diving into each area to determine the overall value of the diamond. 

The GIA is one of the world's most well-known and generally well-respected diamond graders. However, there are many others. 

A diamond certification is necessary because, first and foremost, it ensures that consumers are paying a fair price for their diamonds based on their qualities. 

An uncertified diamond can be problematic, not necessarily because it is of poor quality, but because there is no definitive way of knowing. Without a certificate, it’s unlikely that the seller will be able to fairly and accurately price the diamond or even prove it is real. This can easily lead to consumers paying much higher than the market value for their diamonds. 

At Fyne, our diamonds are graded by the IGI (International Gemological Institute), and we use GIA (Gemological Institute of America) upon request for our bespoke items. We’ve chosen to work with these two graders due to their reputation and experience in the global industry. Our jewellery with lab grown diamonds is valued in the same way as earth-mined diamonds, as they are physically identical.  

By using a reputable grader such as the two mentioned above, we can guarantee the authenticity of our diamonds, ensure our customers are paying a fair price, and offer excellent quality diamonds.

It’s perhaps a common misconception that the higher the price tag, the bigger the diamond. This is not necessarily true, as factors such as clarity, colour, and cut can affect the value. We’ll look at these later. 

Diamond authentication is a notoriously tricky job. In the case of an earth-mined diamond, the grader will often receive a diamond with little to no context about its origin. They will then have to work to detect the qualities of the diamond both under a microscope and by eye.

This is a little easier with lab-grown diamonds, as they are more traceable, but the grading process is the same, as the two are chemically identical. To learn the difference between lab-grown and earth-mined diamonds, we’ve put together a blog on the types of diamonds.

For the reasons mentioned above, even the top grading companies (such as the GIA) don’t offer a guarantee on the grade they choose. It’s also worth noting that grading can vary globally, as no single established ‘gold standard’ exists. This can be due to different training techniques or varied equipment to assess the diamonds. 

That’s why choosing a reputable grading laboratory is so essential. Although no ‘best diamond certification’ exists, those with a wealth of experience are more likely to produce a fair and accurate report. 

Did you know? GIA is the strictest grading lab and will often gives the lowest possible grade for the 4Cs, making it the gold standard in the industry. While GIA is considered the ‘truest’ grading, labs like IGI and HRD are also reputable and trusted. In general, the grade given to the diamond is usually an average of multiple graders (e.g., six people who assess the same stone, with the final grade being the average of their evaluations).

Although standards can vary, there is universal agreement on awarding diamond certification. This assessment, known as the 4Cs, looks at diamond quality and grades.

The process involves studying the diamond both by eye and under a microscope and making four individual assessments on the following: 

• Carat: the diamond weight 
• Colour: the colour within the diamond
• Clarity: the lack of inclusions and blemishes in the diamond
• Cut: the way the diamond has been cut to shape

It’s worth noting that while all of these are factors of the value of the diamond, none of the four alone indicates the price; it’s the combination of all four taken into consideration that produces the final valuation of the diamond. Let’s look at these in a little more detail.

In diamond certification, a carat is a unit of measurement which dictates the weight of a diamond, with one carat equalling 0.2 grams. A higher-carat diamond does not necessarily equate to a larger size, as factors like shape and cut quality come into play here, too. 

Note: Fyne’s diamonds are available in various sizes, including 1.00 carat, 1.5 carat, and 2.00 carat (we can also source higher carat diamonds on request). 

Diamond certificates will assess colour on a scale of D to Z, with D being the most colourless (and therefore most valuable) and Z being a diamond containing the most colour — often a light yellow hue. While D-grade diamonds have the highest ranking, to the naked eye, a mid-range diamond such as G or H will still appear colourless, making it a better-value choice for those less concerned with yellow or brown tints in their diamond.

With diamond jewellery, it’s also worth considering how the mounting or gold used can affect the appearance of the diamond and influence how the colour looks to the eye. All diamonds are assessed unmounted, so the jewellery cannot influence the colour. 

Diamond clarity looks at the number of blemishes and inclusions naturally occurring in the diamond. These happen in formation, and diamonds without inclusions are considered rare. As expected, the fewer inclusions, the higher clarity and, therefore, the higher the value of the diamond. 

On a diamond certificate of authenticity, the scale is from ‘Flawless’ at the highest end to ‘included’ at the lowest. It’s worth noting that while ‘slightly included’ (SI) diamonds may have blemishes visible to the naked eye, ‘very, very slightly included’ (VVS) and ‘very slightly included’ (VS) will not. This means that the diamond won’t be visibly different from a diamond with flawless clarity. So, while this may affect the market value of the diamond, it doesn’t always mean it will be noticeable to the wearer. 

This alone highlights why a diamond certification is so important. Our diamond clarity guide looks at the clarity scale in more detail.

In the diamond authentication process, diamond cuts are measured on a scale from ‘excellent’ to ‘poor’. When assessing a diamond for cut quality, the factors considered include brilliance, symmetry, polish and fire. 

Cut is arguably the most critical factor and one that diamond buyers probably won’t want to compromise on. This is because while many elements of colour and clarity aren’t visible to the naked eye, a poor or average cut diamond won’t reflect the light or dazzle in the same way as its excellent-rated counterpart. 

Cut has the most noticeable impact on the overall aesthetic of the diamond. However, it’s worth noting that it’s a factor purely determined by the skill of the person who has shaped it rather than its naturally occurring colours or blemishes. 

While not all certificates state the origin of the diamond, these days, a more significant number do as standard. Therefore, a diamond certificate of authenticity is an excellent way to ensure your diamond is traceable and fairly priced. When buying a diamond from a supplier or company, it should come with a certification as standard. However, the source of the accreditation can differ, with some being more credible than others. 

While this question is subjective, and there’s no unanimous answer, certain diamond certifiers are more established in the industry than others. So, who certifies diamonds? Some institutions include: 

The GIA are the most well-known diamond certifier and the concept's founder. They are a not-for-profit organisation committed to upholding high standards in the diamond industry. For these reasons, the GIA are one of the two certifiers we use for our diamond jewellery.

Established in 1975, the IGI is from India but operates globally. The IGI is the largest lab of gemologists globally and has had an excellent and thorough reputation throughout its 50-year history. They were also the first laboratory to grade lab grown diamonds, so they are more common and reputable in the lab grown space. This reputation, along with their state-of-the-art equipment, is the reason we use the IGI for our diamond certification at Fyne. 

Established in 1973, the Belgian Graders are world-renowned for their high standards of gemologists and equipment. They come highly recommended in the industry, especially for mined diamonds, and are on par with GIA and IGI for their quality and skill.

Note: There are many other respected diamond graders globally, and when buying a diamond, it’s important to research who is certifying the diamonds to ensure they are reputable. 

AGS is a highly respected laboratory that has developed its cut, colour and clarity standards. They pioneered a lot of industry peer-reviewed techniques, especially around gemstone cutting.

A diamond authentication can increase the appeal and even the value of a diamond. This is important because a certificate will not only give you peace of mind but will also come with a higher resale value.

For those who are new to buying diamonds, here are some of our top tips to ensure you purchase good quality, ethical diamond jewellery:

Not only are these significantly better for the planet, but they’re also more traceable. By knowing the origin of your diamond, you can rest assured that it’s been through an ethical process to get to you. In terms of grading, a lab grown diamond is identical to an earth mined diamond, so the benefits are abundant.

Diamonds without certificates are not often fairly valued, making it unlikely that you’ll get a reasonable price. When buying a diamond or diamond jewellery from a company, you must decipher which organisation they use to grade their diamonds. Legitimate businesses will always be transparent about this. 

Valuations vary between institutes, and some are more reputable than others. We work with diamonds assessed by the International Gemological Institute (IGI) and the Gemological Institute of America (GIA), as these are widely trusted and respected in their offering of diamond certification within the global diamond industry. If your diamond certificate is from a different grader, checking their reputation is essential to ensure fair grading. 

Your diamond may come with a certificate, but how can you verify its authenticity? GIA, IGI, and HRD report checks can be found online and will check the validity of your certificate by studying factors such as the hologram. This way, you can ensure that your certificate matches your diamond and hasn’t been produced fraudulently. 

Did you know? Stones with a diamond grading report usually have a laser engraving of the certificate number on the girdle (the widest part of the diamond that divides the crown and the pavilion). You can use this to cross-check your diamond.