150 Ashley Road, Hale,

Cheshire, WA15 9SA

0161 233 9977


Third Floor, St Johns Court, 19B Quay Street,

Manchester, M3 3HN

0800 080 3535


5 St Christopher’s Pl, Marylebone,

London, W1U 1NA

020 33 271 271

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Diamond Certificates

A diamond certificate is extremely important when buying loose diamonds, diamond jewellery and engagement rings. It validates the quality of the stone and ensures its authenticity

Diamond Certificates

A diamond certificate serves the purpose of the stone’s passport. This authenticating document is issued and printed by an independent laboratory or in-house gemologists. The certificate informs buyers whether diamond is natural and lists its key attributes and qualities.

There are five primary diamond grading laboratories. Only two of the labs listed below have an excellent reputation of grading diamonds unbiasedly and accurately. GIA and AGS are world-renowned and the most respected diamond grading laboratories. GIA invented the current diamond grading system we use today and is the benchmarking authority in diamond grading. AGS are usually known for grading higher quality diamonds with ideal cuts and proportions.

The Main Diamond Grading Laboratories

Diamond Certificates

The Gemmological Institute of America

GIA is the world’s foremost authority on diamonds. GIA is the leading source of knowledge and standards for gems and jewellery

Diamond Certificates

The American Gemological Society

The AGS is famous for its scientific approach to diamond grading, ethical standards and consistency

Diamond Certificates

The Diamond High Council

The HRD is a private foundation established in 1973 as the Diamond High Council and represents the Belgian diamond industry

Diamond Certificates

International Gemological Institute

IGI is the largest diamond and coloured gemstone grading laboratory

Diamond Certificates

European Gemmological Institute

EGL has first introduced diamond clarity rating and specializes in grading diamonds weighing less than a carat

There are many more diamond certification companies around the world, however they do not carry a great deal of authority and as such, should be treated with caution when shopping for diamond engagement rings and diamond jewellery.

Gia And Ags Diamond Certificates

A certificate does not necessarily mean you should buy diamonds with absolute confidence. We would strongly recommend that you only shop diamonds with GIA or AGS certificates when purchasing diamonds online, as these are the only two which actually provide strict and accurate diamond grading.

Diamond Certificates

Less distinguished diamond certificates often assess a diamond as being anything from one to three colour or clarity grades higher, compared to a GIA or AGS certificate. This is why other websites may seem to offer comparable diamonds at a better price (up to 10% cheaper), but in reality won’t be comparing equivalents.

For instance, if a G colour diamond graded from the GIA was graded at EGL, it could be graded as an E colour. So if you were to compare the price of an EGL E colour and a GIA E colour the price could be as much as 20% more, but it will not look the same. It would be cheaper to buy the GIA G colour than the EGL E colour and both would appear the same, so if you were to actually compare identical diamonds, the GIA certified diamond would be better priced.

Here is how much quality may affect diamond price – a 1ct round diamond can vary between £2,500 and £20,000. Both diamonds would weigh the same, however the diamond colour and diamond clarity would be different. That’s why we recommend trusting only GIA and AGS, especially when buying diamonds via the internet.