How to Read a IGI Lab Grown Diamond Grading Report | How to Read a IGI Lab Grown Diamond Grading Report – Brilliant Carbon
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How to Read a IGI Lab Grown Diamond Grading Report

When you buy a significant piece of fine jewelry, you’re investing in a future heirloom. That’s why making sure that your lab-grown diamond is the quality you are looking for is important. To make sure that your lab grown diamond is the color, clarity, cut and carat weight you are paying for, you need a lab grown diamond grading report. An independent diamond grading report, often called a diamond certificate, is a third-party verification of your diamond’s quality. At Brilliant Carbon, all diamonds of 0.50 carats and above are accompanied by a IGI grading report so you can be sure of the 4Cs of diamond quality. Every IGI grading report can be verified at using the report number or the QR code included on the report.

IGI, the International Gemological Institute, is the world’s largest gem grading lab, operating 20 locations around the world Issuing millions of reports annually, for finished jewelry, natural diamonds, lab-grown diamonds and gemstones. IGI is the world’s first gemological laboratory to hold ISO accreditation in both natural and lab grown diamond grading. The Organization for International Standardization 17025 laboratory competence certification is considered the single most important standard for calibration and testing laboratories across the globe, covering all laboratory environments. IGI is also the world’s first gemological laboratory to commit to carbon neutrality, joining the Responsible Jewelry Council, International Precious Metals Institute, and Initiative for Responsible Mining Assurance in an association with SCS Global Services for the purpose of mitigating the laboratory’s environmental impact. IGI doesn’t mine, buy, sell, or trade diamonds so the grade is unbiased and objective.

The IGI Lab Grown Diamond Report includes the gemstone’s description, shape, cutting style, measurements and 4Cs assessment: Carat Weight, Color, Clarity and Cut. Diamond reports may also include a graphic representation of the diamond's proportions and a diagram of its clarity characteristics. The IGI Laboratory Grown Diamond Report provides the same quality and descriptions as the IGI Diamond Report but the color of the report is yellow instead of white. The laboratory grown diamond's girdle is laser inscribed with the report number and the words "lab grown."

Here are the main sections of the IGI Lab Grown Diamond Grading Report and what is included in each section. This glossary will help you understand the IGI grading report for your diamond.

IGI Lab Grown Diamond Certificate


The unique number can be used to verify the authenticity of the report and confirm the grading details using IGI’s online Verify My Report service. This number is also laser-inscribed on the gemstone’s girdle.


The identity and the origin (in this case, lab-grown) as scientifically determined by IGI.


This section describes the outline of the gemstone’s shape and its faceting style. For example, an octagonal diamond could be a radiant cut or an emerald cut.


This specifies the gemstone’s dimensions: minimum and maximum width and length, followed by depth. The dimensions are not the same as carat weight. For example, a one-carat round diamond could be 6.2mm or 6.5mm in diameter. Fancy shapes have varying lengths and widths: an oval can be closer to round or more elongated.


Carat is the standard weight unit for gemstones (not to be confused with karat, which is a measure of gold purity). One carat is 0.20 grams.


Colorless diamond color is graded on a scale from the letter D (colorless) to the letter Z (light yellow, brown or gray). The more colorless a diamond is, the closer to D in the scale, the more expensive it will be. IGI grades diamond color to internationally accepted standards which apply the same way to mined and lab grown diamonds using comparisons to calibrated master stones. All other colors and stronger shades of yellow, brown and gray are classified as fancy colors and are graded on a different scale.


Clarity is graded using 10 power magnification assessing the visibility, size, location, color, number and nature of internal and surface characteristics. IGI grades clarity according to international standards that are the same for mined and lab grown diamonds. The clarity scale ranges from flawless (FL) to I3 (obvious large inclusions.)


Cut of round brilliant is graded on a scale of Ideal to Poor and assesses human craftsmanship factors, including surface polish, faceting symmetry and how the gemstone's overall proportions combine to promote proper physical size appearance and visual beauty components. The better the quality of the cut, the more sparkle and brilliance the gem will have. This cut grade evaluates a diamond's brightness, fire, scintillation, durability, polish, and symmetry. IGI also grades the cut of fancy shaped lab grown diamonds, based on polish, symmetry, proportions and light return. Fancy shape cut grades range from Excellent to Poor. (Ideal is only used for round brilliant diamonds.)


Polish is a sub-component of the overall cut grade. Graded on a scale of Excellent to Poor, it assesses the smoothness and mirror-like finish of each facet resulting from the diamond polishing process.


Symmetry is a sub-component of the overall cut grade. Graded on a scale of Excellent to Poor, it assesses the shape, uniformity, alignment, and junctions of all the gemstone's facets.


Fluorescence is a measure of the finished crystal's reaction to ultraviolet (UV) light, expressed in terms of intensity as None to Very Strong. Very Strong fluorescence can sometimes (but not always) make a diamond look hazy.


Any microscopic inscription that appears on the gem’s girdle, including the report number and the words “lab grown.”


Proportions are measurements of the gemstone's primary and secondary facet groups, largely expressed as average angles and percentages of average girdle diameter.


A map of the gemstone's internal and external clarity characteristics, as observed at 10X magnification, is provided for purposes of information and identification.
The most significant characteristic will be listed first.


This section shows the grading scales for color, clarity, and cut so you can see where your grades fall in the scales. IGI uses the internationally accepted scales for color and clarity, and its own cut grading standard.


This is a photo of your actual diamond. It’s enlarged and not to scale.


A photo of the laser inscription on the gemstone's girdle so you can check to see if it matches the actual gem.

Every IGI paper grading report has a tamper evident security seal with enhancements to protect against counterfeiting.

This QR code can be scanned to take you to the verified digital version of the report posted on the IGI website.

Learn more about IGI lab grown Grading Reports and how they compare in our blog post on IGI vs GIA diamond grading reports.

IGI lab created diamond certificate