Jan 5, 2023
How to Read an IGI Diamond Certificate
If you're considering purchasing a laboratory-grown diamond, it's important to know how to properly evaluate its quality and authenticity. One tool that can help with this process is an IGI (International Gemological Institute) laboratory-grown diamond certificate.
In this article, we'll explain what an IGI diamond certification is and how to read one to make an informed purchasing decision.
What is an IGI Lab-Grown Diamond Certificate?
An IGI diamond certificate is a document that provides a detailed analysis of a lab-grown diamond's characteristics. The certificate includes information about the diamond's size, shape, colour, clarity, and other key features. It also contains a visual diagram of the diamond's proportions and a plot of its inclusions.
The IGI is a leading gemological laboratory operating in the diamond industry for over 45 years. As far as diamond certifications go, its diamond reports – alongside the GIA diamond certification – are highly respected in the industry and are recognised by jewellers and consumers worldwide. An IGI-certified diamond is considered a high-quality diamond that has been thoroughly evaluated and graded by industry standard-bearers.
How to Read an IGI Lab-Grown Diamond Certificate
Now that you know what an IGI certification is, let's review how to read one. Here are the main sections you'll find in a certificate of IGI-graded diamonds and what they mean.
The first section of the certificate includes identification information about the diamond. This consists of the IGI report number, the diamond's shape and cutting style (such as round or princess), and its measurements (such as width and depth).
The Grading Results section includes the diamond's carat weight, as well as its colour, clarity, and cut grades (only applicable to round diamonds for now), which are used to describe the diamond's appearance.
Colour grade: This describes the degree of colour present in the diamond, with grades ranging from D (colourless) to Z (light yellow). The colour of a diamond is determined by comparing it to a set of master stones under controlled lighting conditions. The diamond is assigned a colour grade based on how closely its colour matches that of the master stones.
Clarity grade: This describes the size and number of inclusions present in the diamond, with grades ranging from FL (flawless) to I3 (included). Diamond clarity is determined by examining it under a microscope and assessing the visibility and location of any inclusions.
Cut grade: This outlines the quality of a round diamond's cut, which refers to how the diamond's facets (the flat faces on the diamond's surface) are shaped and angled. A diamond's cut is evaluated based on factors such as its brightness (the amount of light reflected), its fire (the dispersion of light into the colours of the rainbow), and its symmetry (the alignment of its facets). The cut grade of a diamond ranges from Excellent to Poor.
Additional Grading Information
This section for lab-grown diamonds may include details about the diamond's finish, such as its polish, symmetry, fluorescence, and inscription (if any). Here is more information about each of these grading factors:
Polish: The polish of a diamond refers to the smoothness and shine of its surface. A diamond's polish is evaluated based on factors such as the smoothness of its facets and the absence of any surface blemishes.
Symmetry: Symmetry refers to how evenly the facets of a diamond are aligned. A diamond's symmetry is evaluated based on factors such as the alignment of its facets and the overall balance of its shape.
Fluorescence: Fluorescence is a glowing effect that some diamonds exhibit under UV light. The strength and colour of a diamond's fluorescence are graded on a scale from None to Very Strong.
Inscription: An inscription is a minuscule laser-etched message or symbol inscribed on a diamond. An inscription may include the diamond's serial number, logo, or other identifying information and is shown on the certificate as a Laserscribe on the gemstone's girdle.
This section may include any additional information or observations about the diamond relevant to its quality or authenticity. Given the IGI's high grading standards, this may include information about the diamond's origin (CVD vs HPHT), any treatments or enhancements it has undergone, or any other unique characteristics it possesses.
For example, the Comments section may mention if the diamond has been laser drilled (a treatment used to remove inclusions) or if it has been coated with a thin layer of another material to improve its appearance. It may also include any observations about the diamond's fluorescence (a glowing effect under UV light) or its symmetry (the alignment of its facets).
The Proportions section of IGI certificates includes a diagram of the diamond's proportions and measurements. This can help you understand the diamond's overall shape and size. The Proportions section may contain the following information:
Measurements: The diamond's width and depth, measured in millimetres.
Table: The table is the largest facet on the top of the diamond. The table size is expressed as a percentage of the diamond's diameter.
Crown: The crown is the upper part of the diamond, above the girdle. The crown height and angle are expressed as percentages of the diamond's diameter.
Pavilion: The pavilion is the lower part of the diamond, below the girdle. The pavilion depth and angle are expressed as percentages of the diamond's diameter.
Girdle: The girdle is the edge of the diamond. The girdle thickness is defined as a percentage of the diamond's diameter.
The Clarity Characteristics section of an IGI diamond report includes a detailed description of the inclusions present in the diamond, viewed at 10x magnification. Red symbols indicate internal characteristics, while green symbols indicate external characteristics.
It may include the location of each inclusion within the diamond, such as on the crown (top), girdle (edge), or pavilion (bottom). It may also detail the type of inclusion, such as a crystal, feather, or knot.
The Grading Scale section of the report explains how the diamond's colour and clarity were determined. The colour of a diamond is graded on a scale from D (colourless) to Z (light yellow). The clarity of a diamond is graded based on the size and number of inclusions present in the diamond. The clarity scale ranges from FL (flawless) to I3 (included).
Why is it Important to Read an IGI Lab-Grown Diamond Certificate?
Reading an IGI laboratory-grown diamond certificate can help you make an informed decision when purchasing a lab-grown diamond. It provides detailed information about the diamond's characteristics, including its size, shape, colour, clarity, and inclusions. This can help you understand the quality and value of the diamond.
In addition, an IGI certificate can also help to verify the authenticity of the diamond. It includes a unique identification number that can be used to track the diamond's history and verify that it is a genuine laboratory-grown diamond. This is particularly important for consumers who want to ensure that they are purchasing a diamond that has been ethically and sustainably produced.
IGI-certified diamonds are also useful when it comes to insuring your diamond. Many insurance companies require a professional evaluation of the diamond before providing coverage. An IGI diamond report can serve as this evaluation and help you to secure the appropriate insurance coverage for your diamond.
In summary, an IGI lab-grown diamond certificate is the gold standard for anyone considering the purchase of a laboratory-grown diamond. The IGI 's world-leading diamond grading reports provide detailed information about the diamond's characteristics and help to verify its authenticity and quality.
By understanding how to read an IGI lab-grown diamond certificate, you can make an informed and confident decision when choosing the perfect diamond for you. To start now, check out Cullen Jewellery’s latest lab-grown diamond engagement ring range here.