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The Certificate (the Fifth C)

The Certificate (the Fifth C)


A diamond certificate (also known as the diamond grading report) verifies the carat weight, colour and clarity grades, dimensions and other attributes such as girdle thickness, polish and symmetry. Round brilliant diamonds sometimes also have the cut grade shown on the certificate.

The certificate is so important that it’s often referred to as the fifth ‘C’ (alongside the well-known Four C’s of Cut Grade, Colour, Clarity and Carat weight). 

Whenever you consider a diamond purchase, you should always make sure the diamond is certified by an internationally recognised diamond laboratory. Sadly, some diamond retailers self-certify their diamonds, overstating their quality, in order to increase their profit margins. Because of this, it’s crucial that a diamond is certified through an unbiased and professional examination undertaken by an internationally recognised diamond laboratory.

Diamond grading is an exact science - so the stone should be carefully evaluated and graded using established criteria. If in doubt, ask which laboratory provided the certificate and ask to see it. Never buy an uncertified or self-certified diamond.

Click here for more details about the differences between certified and non-certified diamonds.

There’s Always an Exception!

Most diamond retailers use their own criteria to grade the cut quality of non-round diamonds. That’s because there are no universally accepted standards for cut grading these shapes. See Cut Grade for more information.

Ensuring your diamond is certified by an independent laboratory is one thing. But each lab has developed its own set criteria for grading diamonds and some are stricter than others

Click here to see the differences between the grading of each of the major laboratories

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