Diamond Certificate

A diamond certificate is an independent statement verifying your diamond's exact characteristics – weight, color, clarity, cut, and proportions. It provides assurance and acts as a receipt for exactly what you are getting. At Coliène, every diamond from 0.30 carat comes with a certificate from a reputable gemological institute.

When you buy a diamond, you want to know exactly what you're getting. Two diamonds that look identical to the naked eye can differ significantly in quality and value. A certificate from an independent laboratory provides you with objectively verified facts about your stone.

GIA is the world's most renowned and respected gemological institute. It was GIA that, in the 1950s, developed the 4 C's grading system, which is now the industry standard worldwide.

A GIA certificate is the most recognized reference in the diamond world. GIA is a non-profit organization with no commercial interests, which means their grading is completely independent and consistent.

Known for
Strict and consistent grading. Considered by many to be the toughest grader – an H color according to GIA can correspond to a better grade from other institutes.

IGI is one of the world's largest gemological institutes with laboratories in Antwerp, Mumbai, New York, and Hong Kong, among others. IGI has become particularly popular for the certification of lab-grown diamonds, where they are market leaders.

IGI certificates are well respected in the industry and used by many leading jewelers worldwide. Their grading system follows the same principles as GIA's 4 Cs.

Known for
Market leader in the certification of lab-grown diamonds. Fast processing time and a broad global network.

A typical certificate contains the following information:

Report number
A unique ID number that allows online verification of the certificate on the institute's website.

Shape and Cut
The diamond's shape (e.g., round brilliant) and the quality of its cut.

Measurements
The diamond's exact dimensions in millimeters.

Carat Weight
The diamond's weight with two decimal places of precision.

Color Grade
On the D–Z scale (or equivalent Nordic system).

Clarity Grade
From FL (Flawless) to I3 (Included).

Cut Grade
From Excellent to Poor (applies to round brilliant diamonds).

Symmetry and Polish
Additional quality measures for light reflection.

Fluorescence
Any UV fluorescence, graded from None to Strong.

Proportion Diagram
A graphic overview of the diamond's proportions.

At Coliène, all diamonds of 0.30 carats and larger come with certificates from GIA or IGI. For smaller diamonds (under 0.30 carats), which are often used in eternity rings, we guarantee the same quality standard but without individual certificates from independent institutes. In these cases, we issue a certificate where we vouch for their quality.

Regardless of the certification institute, we guarantee that all our diamonds meet the following criteria: excellent cut, carefully selected for clarity and color, and always conflict-free.

Both GIA and IGI offer the option to verify your certificate online using the report number. This is a simple way to confirm that the certificate is authentic and that the information is correct.

Do you have questions about your diamond's certificate, want to understand what a specific grading means, or are you curious about the certificates for a particular ring you are interested in? Contact us – we are happy to share detailed certificate information and help you interpret it.

Contact us if you have preferences regarding which institute should issue the certificate, and we will ensure it is taken into account when you place your order.

Contact us →