Diamond

The Ultimate Guide to Diamond Certification

Purchasing a diamond? Learn more about certified diamonds, gemological grading laboratories, and the diamond certification process here.

By 

Meyme Nakash

 |  August 29, 2025

Not all that sparkles is certified, and when it comes to buying a diamond, an official grading report plays a crucial role in verifying the stone’s quality, authenticity, and value. Diamond certification, or diamond grading, can only be issued by a recognized gemological laboratory, the most prominent of which are the Gemological Institute of America (GIA), American Gem Society (AGS), and International Gemological Institute (IGI), among others. A grading report provides an unbiased assessment of a diamond’s characteristics, including the four C’s — cut, clarity, color, and carat weight — among other attributes, which we discuss in greater detail below.

Though buying a certified diamond from the start is certainly ideal, it’s never too late to get your stone evaluated, offering you peace of mind about a past purchase and an official record of the diamond’s qualities. Here, we answer the most common questions about diamond certification, from why it’s important to the different gemological laboratories. 

In This Article

• What Is a Certified Diamond?
• What Information Is on a Diamond Certificate?
• The Top Diamond Grading Laboratories
• Why Is Diamond Certification Important?
• How to Get Your Diamond Certified 

The Ultimate Guide to Diamond Certification

Diamond certification helps buyers make diamond purchases with confidence — relying on facts about the stone’s worth rather than sales pitches. 

What Is a Certified Diamond?

A certified diamond is a diamond that a recognized gemological laboratory (read more below) has evaluated and graded. The certification process involves a thorough analysis of the diamond’s key characteristics (which we explain here), resulting in an official detailed grading report. This diamond certificate acts as a trusted third-party guarantee that the diamond meets specific standards, thereby protecting buyers from misinformation or overpaying for a diamond. Certified diamonds are easier to insure and resell than uncertified diamonds; a certificate serves as official documentation of the diamond’s value, which is especially important for sentimental purchases such as engagement rings.  

Read More: How to Choose and Buy an Engagement Ring

What Information Is on a Diamond Certificate?

As mentioned above, a diamond certificate contains a detailed assessment of a diamond’s key attributes — most notably, its cut, clarity, color, and carat weight. The cut grade reflects how the diamond’s facets interact with light (which affects its sparkle); this includes information about the diamond’s proportions, symmetry, and polish — not its shape. The clarity grade is a measure of the presence of internal flaws, also called inclusions, and any surface imperfections. Unlike fancy color diamonds, which have a different grading system that values saturation, a diamond’s color grade tells how colorless it is on a scale from D (transparent) to Z (noticeably yellow or brown). Lastly, carat weight is how much the diamond weighs. All of these characteristics have a significant impact on the value of a diamond, but they’re not the only factors that go into a diamond certificate. 

In addition to the four C’s, a grading report offers information about the diamond’s shape and fluorescence, or how it reacts to ultraviolet light. It also features a clarity plot, or diagram that maps out any visible inclusions. Some reports include whether a diamond has a laser inscription for identification. 

Each diamond certificate has a grading report number, the name of the issuing laboratory, and, often, a QR code or online verification link that allows buyers to easily confirm the diamond’s credentials from their mobile device. 

Read More: Carats vs. Karats: What’s the Difference?

The Top Diamond Grading Laboratories

There are several respected diamond grading facilities in the world, each with its own reputation, grading standards, and areas of specialization. GIA is the gold standard for diamond certification due to its strict grading practices — specifically, in assessing a stone’s color and clarity. It’s often the top choice for buyers who want the most accurate evaluation of a diamond’s quality, but the laboratory grades only unmounted stones — making it challenging to certify diamonds already set as jewelry.

AGS is another highly regarded laboratory, known for its focus on light performance and cut grading — specifically, for brilliant-cut diamonds. IGI is also a reliable entity that’s popular in global markets, thanks to its affordability relative to GIA and AGS, as well as faster turnaround. It’s frequently used to certify lab-grown diamonds, in addition to natural diamonds. Both AGS and IGI offer grading reports for diamonds already set in jewelry. 

Based in Switzerland, Gübelin provides certification services for diamonds and other natural gemstones through its Gübelin Gem Lab, but it is best known for certifying the geographic origin and any treatments used on colored gemstones. It also offers what it calls a Jewellery Passport, an AI-powered, lower-cost report for smaller stones. There’s also the European Gemological Laboratory (EGL), which once had a strong international reach but has become known for inconsistent and lenient grading, thereby reducing its reliability. 

La Patiala strongly recommends GIA for unmounted diamonds, AGS and IGI for mounted diamonds, and Gübelin for colored gemstones.

Why Is Diamond Certification Important?

Diamond certification is a critical layer of protection and transparency for what can be one of the most meaningful purchases a person makes. It provides an objective, expert evaluation of a gemstone’s quality, helping buyers purchase jewelry with confidence. This is because without certification, it’s nearly impossible to verify a diamond’s important qualities, such as its cut, color, clarity, and carat weight, which directly affect its value and appearance. A diamond grading report serves as a reference point for this information, protecting you from purchasing a misrepresented diamond and, in turn, overpaying for what you’re getting. 

A diamond certificate is also essential for insuring and reselling a diamond. If you ever need to replace a lost or stolen diamond, an official grading report is often required by insurers to determine coverage. Likewise, should you ever decide to resell a diamond, having proper documentation adds legitimacy to the sale, increasing its appeal to potential buyers.

How to Get Your Diamond Certified 

To get your diamond certified, you’ll need to submit it to a trusted gemological laboratory for professional assessment and grading. You can start by choosing a facility, such as GIA, AGS, IGI, and so on, and reviewing their submission guidelines. Many laboratories allow you to submit a diamond directly to them, provided you’re comfortable using insured shipping methods, or through a certified jeweler or gemologist who will take care of the paperwork and the diamond’s transit to their facility. Once your diamond arrives at the laboratory, experts will analyze it using advanced instruments and software, including spectroscopy, X-ray, and microscopy technologies. 

After the evaluation is complete, the laboratory will issue an official grading report that includes detailed information about a diamond’s qualities, along with diagrams and laser inscription details, if applicable. This entire process usually takes a few weeks to complete, depending on the facility’s workload. GIA offers a same-day rush service for certain types of diamonds, in which they evaluate a stone the same day they receive it; you can submit it by mail or by walking into GIA’s New York laboratory (walk-in clients receive priority). Looking to certify a lab-grown diamond? The GIA has developed a system specifically for describing the qualities of artificially produced diamonds, which it plans to implement as part of its lab-grown diamond certification services by the end of 2025.

It’s imperative to note that diamond certification is not the same as an appraisal. In other words, a grading report doesn’t assign the monetary worth of a diamond; rather, it provides a technical assessment of its quality, which helps determine a diamond’s value. Some companies, including IGI, offer both. 

Read More: Why Are Diamonds So Expensive?

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