A GIA or IGI certificate documents a natural diamond's carat, colour, clarity, and cut, as graded by an independent laboratory. Both labs use the same 4Cs framework, though GIA has a reputation for applying grades more strictly. Diamond Brothers buys natural diamonds only and does not buy lab-grown diamonds. This guide covers what each certificate confirms, whether the lab named on the certificate matters when selling a natural diamond, and where a certificate fits into the selling process. Diamond Brothers has more than 30 years of experience and sits in the heart of the Antwerp diamond district.
What Does a GIA or IGI Certificate Actually Confirm?
A certificate confirms a diamond's carat weight, colour grade, clarity grade, and cut quality, assessed by trained gemologists at an independent laboratory. This documentation gives an objective reference point for the diamond's grading. Certificates also record a diamond's measurements and proportions in detail, along with a unique report number that can be checked on the issuing laboratory's website. A diamond with a certificate arrives at Diamond Brothers with its core facts already documented, and the diamond still goes through a full assessment during valuation.
What Is the Difference Between GIA and IGI?
GIA, the Gemological Institute of America, and IGI, the International Gemological Institute, are two widely recognised diamond grading laboratories. Both use the same 4Cs system, and GIA has a reputation for applying colour and clarity grades more strictly, which means a diamond graded G by GIA might receive a slightly higher grade from IGI for the same stone. The difference shows most at the margins between adjacent grades, where a diamond sitting between two colour or clarity categories can land differently depending on which lab issued the report.
Does the Certificate Lab Matter When Selling a Diamond?
Diamond Brothers welcomes certificates from GIA, IGI, and HRD for natural diamonds, and confirms carat, colour, clarity, and cut through its own assessment, whichever lab issued the report. The offer comes from that assessment, with the certificate serving as a documented reference for the diamond's grading.
Are Certificates From Other Grading Labs Accepted?
Yes, certificates from other recognised laboratories, including HRD Antwerp, are accepted alongside GIA and IGI reports. HRD, the Hoge Raad voor Diamant, is based in Antwerp and grades diamonds against the same core 4Cs framework. A certificate from any established, independent grading lab gives Diamond Brothers a documented starting point for assessment.
Does Having a Certificate Affect the Offer?
A certificate gives an immediate, documented reference point for the diamond’s grading. A certified diamond's carat, colour, clarity, and cut are already recorded, which removes guesswork. A diamond without a certificate still receives a full valuation, since certified gemologists grade the stone directly during assessment. The diamond's actual grading sets the price.
Can a Certificate Be Checked for Accuracy?
Yes, every certificate carries a unique report number that can be checked on the issuing laboratory's website. GIA and IGI both offer online report-checking tools where a certificate number confirms the report is genuine and shows the diamond's recorded grading and measurements. During valuation, certified gemologists examine the diamond directly, which shows whether the certificate matches the stone in front of them.
What Happens if the Certificate Doesn't Match the Diamond?
If a certificate's details differ from the diamond it accompanies, Diamond Brothers assesses the diamond on its own actual grading. This can happen when a certificate was issued for a different stone, when a diamond has been altered since certification, or through an honest mix-up between papers from several pieces. The diamond's own carat, colour, clarity, and cut, confirmed through direct assessment, determine the offer. A mismatched certificate still leaves the diamond eligible to be sold, and only the certificate itself loses its value as a reference for that stone.
How to Sell a Certified Diamond in Germany, Austria, Switzerland and Luxembourg
Selling a certified natural diamond to Diamond Brothers follows three steps, whether it comes from Germany, Austria, Switzerland, or Luxembourg.
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Fill in the free online form with basic details and a few photos of the diamond, and add the certificate's lab and report number if one exists.
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Choose how the diamond reaches Diamond Brothers, with any certificate travelling alongside it: free, insured FedEx pickup, a private appointment at the Antwerp office, or a local in-person meeting, since Diamond Brothers' associates travel across Europe regularly. For pieces shipped from Switzerland, Diamond Brothers prepares the customs paperwork.
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Get a free valuation after certified gemologists examine the natural diamond and review any certificate that comes with it. Accepting the offer is optional, and we transfer your payment the moment you accept our offer.
Valuation happens the same day the diamond arrives.
Get a free valuation for a certified diamond today.
FAQ
Does the certificate lab matter when selling a diamond?
Diamond Brothers welcomes certificates from GIA, IGI, and HRD and confirms the diamond's grading through its own assessment, whichever lab issued the report.
Does an old certificate still count?
An older certificate still counts as a documented reference point, and Diamond Brothers confirms the diamond's actual grading directly during valuation, whatever the certificate's age.
Is a certificate required to sell a diamond?
A certificate isn't required. Certified gemologists assess the diamond directly during valuation, whether or not it has paperwork.
Can a lost certificate be replaced before selling?
A lost certificate doesn't need replacing before selling. Diamond Brothers grades the diamond directly during assessment, without requiring the original paperwork.
Which certificates does Diamond Brothers accept?
Diamond Brothers accepts natural diamonds with certificates from GIA, IGI, HRD, and other established independent labs, as well as natural diamonds without a certificate.
