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Diamond certification

Diamond Certificate

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What is a certified diamond?

If a diamond has been independently graded by a gemological laboratory and supplied with a report detailing the size and quality of the diamond, it is termed a certificated or certified diamond. Diamond certification is widely available for diamonds above 0.3ct.

To cover the cost of certification, and because certification gives customers some assurance that the diamond is of the stated size and quality, certified diamonds tend to be more expensive than uncertified diamonds of the same grades. 

There are more than twenty organisations around the world that offer these reports. The Gemological Institute of America (GIA) and the International Gemological Institute (IGI) are among the best-known and most reputable of these. Other notable labs include the Diamond High Council (HRD) in Antwerp and the American Gemological Society (AGS).

Are lab-grown diamonds certified?

Lab Grown Diamond Certificate
IGI Lab Grown Diamond Certificate

All types of diamonds can be certified, whether they are mined or lab-grown diamonds and whether they're white or fancied-coloured diamonds.

At Ingle & Rhode, most of our lab-grown diamonds are supplied with IGI certificates, but some come with GIA certificates. With our mined Canadian diamonds, it is the other way around, with the vast majority being GIA-certified.

What do diamond certificates include?

There are minor variations in the way that the different gemological labs grade diamonds, but they all focus on the 4Cs:

Note that most laboratories only provide a Cut grade for round brilliant cut diamonds since there is limited consensus on the ideal proportions of all other shapes (known as fancy cut diamonds).

Diamond certificates also provide Polish and Symmetry grades (for diamond shapes) and indicate whether the diamond exhibits a phenomenon called fluorescence.

A diamond certificate should also state whether a diamond is mined or lab grown and whether it has been subject to any treatment to enhance its appearance.

Finally, the report should have a unique serial number which is also inscribed on the diamond's girdle, to confirm that the certificate belongs to the diamond in question.

Diamond laser inscription
Laser inscription on the girdle of a diamond with IGI certificate number LG10244202

Certificates of origin

Some diamond certificates will tell you the diamond's origin, but most won't, in which case, a separate certificate of origin is required.

CanadaMark certificates of origin
CanadaMark Certificates of Origin

Ingle & Rhode supplies mined Canadian diamonds. Not only are these guaranteed conflict-free diamonds, but Canada has strict environmental regulations that ensure diamond mines manage and minimise their impact on flora, fauna, and local communities.

All of our Canadian diamonds of 0.3ct or more come with a CanadaMark certificate of origin.

Should you buy a diamond based on the certificate?

Suppose the diamond you're considering has been certified by a reputable independent authority such as the GIA or IGI. In that case, you can be assured that the diamond will be as advertised.

If a diamond has not been certified, or the certification comes from a less reputable authority (or worse still from the jeweller themselves), there is a risk that the size and/or quality of the diamond has been exaggerated.

However, even if a diamond has been certified by a reputable authority, viewing some diamonds in person is sensible if you can. This is helpful because it will allow you to get a sense of the differences in size between different carat weights and will also help get you comfortable with what different colour, clarity, and cut grades look like 'in the flesh' and side by side.


Is it essential to have a diamond certificate?

Purchasing a diamond with a reputable grading report or certificate is highly recommended for diamonds from 0.3ct and above. You can still buy a beautiful, high-quality diamond without certification, but you are taking a risk.
Note that diamonds below 0.3ct are rarely supplied with diamond certificates since the cost of certification starts to become disproportionate to the value of the stone.

How do I check if my diamond is certified?

The best way to ensure your diamond is certified by an independent laboratory is to check before you buy and ask to see a copy of the certificate. However, If you already have a diamond and aren't sure if it's certified, you can search for a laser inscription on the girdle of the diamond, which, if present, should include the name of the laboratory and the report number. This can only be viewed under magnification, so you may need to take it to a local jeweller and ask them to help you.

Note, however, that this is not a fail-safe way to confirm if a diamond is certified because not every certified diamond has a laser inscription. Also, in rare cases, uncertified diamonds have had laser inscriptions added to pass them off as certified stones. If you find an inscription, go to the laboratory website and search for a copy of the certificate, then check whether the diamond you have seems consistent with the details on the report.

Is a diamond without certification worth less?

In theory, the value of a diamond is not determined by whether or not it has a certificate, though, in practice, certified diamonds do tend to be more expensive than uncertified diamonds because sellers want to recover the additional cost of certification, and because buyers are willing to pay a premium for the reassurance that the stone they are buying is as advertised.


Although diamond certification isn't absolutely essential, it is highly advisable to only purchase diamonds of 0.3ct and above that come with a certificate from a reputable gemological authority. This will ensure that the diamond you receive is of the advertised size and quality.

However, diamond certification is not enough on its own. Just because a diamond is certified doesn't mean that it is necessarily a high-quality stone or good value. You still need to consider the 4Cs when choosing a diamond, whether certified or not.

Furthermore, most diamond certificates or reports do not tell you anything about the origin of a mined diamond. For this reason, if you are buying a mined diamond, we offer Canadian diamonds that come supplied with CanadaMark certificates, guaranteeing the provenance of the stone and the fact that it is conflict-free and ethically sourced.

David Rhode
Together with Tim Ingle, David created Ingle & Rhode to offer a better alternative to the traditional luxury brands. Since 2007, we’ve provided our customers with genuinely ethical engagement rings, wedding rings and fine jewellery – free from conflict diamonds, dirty gold and child labour. With more than 16 years experience in the jewellery industry, David has deep expertise in diamonds, gemstones and jewellery design and manufacturing.