Diamond Certification in Antwerp: GIA, HRD & IGI

Diamond certification — also called a diamond grading report — is an official document issued by an independent gemological laboratory. It provides an objective assessment of a diamond's quality based on the 4 C's: cut, colour, clarity and carat weight. Think of it as a diamond's passport: a detailed record that confirms exactly what you are buying.

A certificate is not the same as an appraisal. While an appraisal estimates a diamond's monetary value for insurance purposes, a grading report describes the stone's physical characteristics without assigning a price. The certificate remains valid regardless of market fluctuations, which makes it essential for resale and comparison shopping.

As a certified diamond dealer in Antwerp since 1987, Diamantwerp works exclusively with GIA, HRD and IGI — the three most trusted diamond grading laboratories in the world.

Every diamond certificate from a reputable lab covers a standard set of characteristics. While the layout and terminology may vary slightly between GIA, HRD and IGI, the core information is consistent.

Additional details often include polish, symmetry, fluorescence, and proportions such as table percentage, crown angle and pavilion depth. Together, these measurements give a complete picture of the diamond's optical performance.

Hundreds of gemological laboratories operate around the world, but only three have earned widespread trust among diamond professionals and consumers alike. At Diamantwerp, we work exclusively with GIA, HRD Antwerp and IGI because of their strict grading standards, global reputation and reliable consistency.

All three laboratories evaluate diamonds using the same fundamental criteria — the 4 C's — but they differ in grading strictness, report formats and regional recognition. The comparison below highlights the most important differences.

When a laboratory certifies a diamond, the stone can be sealed inside a tamper-proof transparent container — linking the certificate physically to the diamond. If the seal is intact, it guarantees that the diamond inside matches the certificate exactly. Sealing also keeps the stone clean and protected from oils and dirt.

As an alternative or addition to sealing, laboratories offer laser inscription: a microscopic engraving of the certificate number directly on the diamond's girdle. This inscription is invisible to the naked eye and can only be read under magnification. It provides a permanent form of identification, useful for insurance claims, theft recovery and personal peace of mind.

GIA includes laser inscription as standard on most reports. HRD and IGI offer it as an optional service. At Diamantwerp, the majority of our diamonds come sealed or laser-inscribed for your protection.

Dozens of other laboratories exist — including EGL, AGS, NGTC and various regional labs. While some of these may be competent, many apply inconsistent or overly generous grading standards. A diamond graded "F colour, VS1" by a less reputable lab might receive a lower grade from GIA or HRD, which means you could be overpaying for a stone that does not match its certificate.

We chose to work exclusively with GIA, HRD and IGI for three reasons:

1. Consistency. These labs produce reliable, repeatable results. A grade on their certificate accurately reflects the diamond's true quality.
2. Global recognition. Whether you buy, sell or insure your diamond anywhere in the world, certificates from these three labs are universally accepted.
3. Transparency. Every certificate can be verified online through the issuing lab's database, giving you complete confidence in your purchase.

As a family-run diamond dealer in Antwerp since 1987, our reputation depends on the quality of every stone we sell. Working with the world's most trusted labs is a fundamental part of that commitment.

Browse our full collection of GIA, HRD and IGI certified loose diamonds — available from our showroom at Pelikaanstraat 62, Antwerp, or shipped next day.

Reading a diamond certificate can seem overwhelming at first, but once you understand the key sections, it becomes straightforward. Here is what to focus on:

1. Verify the report number. Visit the lab's website and enter the unique report number. This confirms the certificate is genuine and has not been altered.
2. Check the 4 C's. Compare the cut, colour, clarity and carat grades against your expectations and budget.
3. Review proportions. For round brilliants, look at the table percentage (ideally 54–58%), crown angle and pavilion depth. These numbers determine how well the diamond sparkles.
4. Check fluorescence. Slight fluorescence (None to Faint) has no visible impact. Strong fluorescence can sometimes make a diamond appear hazy, but can also reduce cost.
5. Study the clarity plot. The diagram shows where inclusions are located. Centre inclusions are more likely to be visible; edge inclusions can often be hidden by a setting.

If you need help interpreting a specific certificate, our team at Diamantwerp is happy to walk you through it. Get in touch for a free, no-obligation consultation.