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What is Diamond Certification?

Independent certification is how you can be sure that you're getting a quality diamond that’s accurately graded without bias. All Blue Nile loose diamonds are analyzed and graded for quality by the Gemmological Institute of America (GIA), one of the most respected and accurate labs in the diamond industry. Additionally, all Astor by Blue Nile™ diamonds are certified for light performance by GemEx, the leader in light measurement. To verify a diamond's quality before purchase, be sure to review its Diamond Grading Report or Diamond Dossier and the GemEx certificate if you are buying an Astor by Blue Nile™ diamond. It’s also good to know that your purchase of a custom-built ring, pendant or pair of earrings from Blue Nile comes with an appraisal that includes the retail replacement value of the item for insurance purposes.

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The difference between Diamond Grading Reports and Diamond Dossiers®

Aside from your home, purchasing a diamond might be one of the biggest investments you make in your lifetime. That’s why diamond grading (a.k.a certification) is so important. The two main reports issued by the GIA are the Diamond Grading Report and the Diamond Dossier®. And, while similar, there are important distinctions.

  • Diamond Grading Report: Many consider this to be the blueprint of a diamond. Starting with the 4Cs – cut, clarity, colour, and carat – the report includes precise measurements and shape, as well as a plot or map of the individual diamond’s characteristics. The diamond grading report will also note if the diamond has a girdle inscription, and will describe important characteristics beyond the clarity grade.
  • Diamond Dossier®: This dossier offers the same grading information as the Diamond Grading Report, minus the plotted diagram. To prove authenticity, the dossier also includes the laser inscription number on the diamond’s girdle.

Review a sample GIA Report

Familiarize yourself with the look and orientation of a GIA Diamond Grading Report. You’ll find a GIA grading report on the product page of every loose diamond on the Blue Nile website, but you can also download a sample below. Note the 4Cs, plotted diagram, and mapping of the stone’s proportions. You’ll find a GIA grading report on the product page of every loose diamond on the Blue Nile website.

Print Sample Report

Is it important to get a Diamond Grading Report when you buy a diamond?

Your diamond certification is so important, it’s sometimes referred to as the 5th C. Diamonds with a GIA grading report will help you down the road to:

  • Confirm the quality of your diamond
  • Help to verify ownership for repair or insurance
  • Prove useful if you want to resell a diamond

All Blue Nile diamonds include a GIA Diamond Grading Report

As stated before, every loose diamond sold by Blue Nile has been analyzed and graded by the Gemmological Institute of America (GIA). Since 1931, this non-profit laboratory has ranked among the most respected in the diamond industry, setting the standards for impartial quality review and education.

Watch Out: The U.S. Federal Government legally permits jewellers to be off by one colour and clarity grade. It might sound like a small margin of error, but it can mean that you pay hundreds or thousands of dollars more for your stone. Never buy a diamond without a GIA report.

Do all labs grade diamonds the same way?

Definitely not. While Blue Nile adheres to GIA standards, diamond grading protocols, systems and nomenclature can vary by organisation. Other labs besides the GIA include the American Gem Society (AGS), European Gemmological Laboratory (EGL), International Gemmological Institute (IGI), and Hoge Raad voor Diamont (HRD).

Learn more about diamond documentation

If you are interested in a diamond and a certificate is not available for viewing on the site, simply contact a diamond and jewellery consultant at or 0800-440782.