The Guide to Diamond Certificates

What is a diamond certificate?

When a diamond has been certificated it means it has been examined by an independent gemological laboratory who provide an unbiased and expert assessment of the quality and grading (the 4Cs) of a diamond. Some jewellers will provide their own in-house 'certificate', but this is not recognised as an industry standard in the same way an independent certificate is.

A diamond certificate will provide you with every important detail about a diamond, from the cut, colour, clarity and carat weight, to the proportions, polish and symmetry. You will also commonly find a sketch of the diamond to illustrate the inclusions in the stone and a unique identification number which belongs only to that diamond.

All of the major diamond certification laboratories have an online checking system which you can search using the ID number so you can research with complete peace of mind when making your purchase. A diamond certificate is usually referred to as the 5th 'C' when it comes to diamond buying and provides complete transparency when buying a stone.


What are the best certificates?

Certificates are a good thing to look for when purchasing a diamond, but be aware as not all certificates are created equal and some are more detailed than others. Below are three of the top gemmological laboratories worldwide who provide the most detailed and highest quality diamond reports:

GIA - Gemmological Institution of America

The GIA is regarded as the highest authority in certification and education in diamonds and precious gemstones since its inception in 1931.

A non-profit organisation which created the standards by which we measure the 4Cs today, they employ the most stringent of testing standards of any certification body.

They have been the International benchmark for diamond certification since they created the first reports in 1953. As well as creating the 4Cs they also provide free education guides as well as offering jewellery and gemstone degrees worldwide.


IGI - International Gemmological Institute

The IGI is the largest certification body in the world, with 17 offices globally.

They have employed cutting edge industry standards since they first opened their office in Antwerp in 1974. Antwerp is well known as the diamond capitol of Europe and IGI have the oldest offices there.

Continually employing the most state of the art certification techniques, from laser embossing diamonds with their unique certificate number to offering repair and re-cutting services for damaged diamonds.


EGL - European Gemmological Laboratory

The European Gemmological Institute differs from GIA and IGI in that they are the worlds largest independent certification laboratory who offer multiple levels of report depending on the detail you need.

They have a network of gem labs all over Europe with their head office in Czechia.

Their office first opened back in 1974 and have been a well respected institution since then.


Maple Leaf Diamonds

Maple Leaf diamonds are mined in Northern Canada and are some of the most beautiful diamonds in the world. Each diamond is 100% natural and untreated, and are all laser inscribed so each diamond can be tracked from mine to store.

This also ensures that all their jewellery is ethically sourced, as well as providing us with some of the most unique and beautiful jewellery.

There are 4 active diamond mines in Canada now. Three in the northwest territories, and one in Quebec. These mines make Canada the third largest diamond producer in the world.

After decades of exploration in the extreme weather conditions of Northern Canada the first mine was discovered in 1991, it is situated just 200km south of the Arctic Circle.


How to read a diamond certificate

When you know what to look for, a diamond certificate can be pretty easy to read, but if you haven't seen one before - which will be the case for most people it can be a bewildering.

To give you an example, we have found a sample report from the GIA. Each certificate regardless of origin, will have the table of all the possible grades for each of the C's which are the most important gradings to review when making your decision.

You can find out more about the 4Cs in our guide. You will also find that any jewellery consultant in a store will be able to explain the details to you. Below we have highlighted these most important parts but generally speaking, reports are self explanatory:


Frequently asked questions

Is Certificated better than non-certificated?

When coming to choose a diamond, certification provides reassurance in what you are buying is verified in its overall quality. However, as i'm sure you can imagine, certification comes with an additional cost.

A certificated diamond will come in at a premium when compared to a diamond the same quality but without a certificate. The cost of certification depends on the laboratory used and the size of the diamond but, you should expect to pay between £100-£300 for most stones.

What if a diamond doesn't have a certificate?

As long as you buy from a reputable jewellers they should be able to provide you with the information you need on your diamond purchase. Most jewellers will even provide you with some diamond grades if you ask them so you can have the information without the additional cost of a certificate.

I'm buying a certified diamond but i've not heard of the lab before

If you are going for a certificated diamond, be sure to check the credentials of the certificating company. Some are more highly regarded than others, so do your research or try and stick to the more well known ones if possible.

Is there really a benefit to getting a certificate?

Having a certificate is like a security blanket for your purchase, it means your diamond is independently graded and you don't need to take the jewellery consultants word for it. You will also find your certificate beneficial if you were to ever sell your jewellery or pass it down through your family.

Have A Question?

Contact us by phone at 0141 221 5855 or by email at [email protected]. We love our work and will be happy to help you with your query, we can also book a convenient time for a consultation to find the exactly what you need.


Simon Porter

Director, James Porter & Son

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Simon is the 5th generation Porter to look after the day to day running of the James Porter & Son store since its inception in 1858. Working alongside his father since 1995 and eventually taking over the reins full time in 2007.

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