How Lab-Grown Diamonds Are Graded and Certified: Why It Matters

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Are you interested in learning more about how lab-grown diamonds are graded and certified? Then read this guide to understand how lab-grown diamonds are graded and certified.

Lab-grown diamonds are a better alternative to mined diamonds, but they require an understanding of diamond grading. That’s why it’s critical to understand what goes into evaluating lab-grown diamonds before making any purchase.

In this guide to how lab-grown diamonds are graded and certified, we’ll discuss the history of diamond grading, how lab-grown diamonds are graded today, and why they need to be certified by reputable organizations. We also share tips and recommendations and teach you how to use the diamond grading report and certificate to your advantage when shopping for a lab-grown diamond.

Read on to learn all about how lab-grown diamonds are graded and certified!

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What is Diamond Grading?

Diamond grading is the process of assessing a diamond’s characteristics and assigning it a quality grade. This helps buyers make informed decisions when purchasing diamonds, as they can easily compare different lab-grown diamonds based on their grades. Grading of lab-grown diamonds is important because it provides an objective measure of quality that allows buyers to accurately assess the value of a lab-grown diamond before making a purchase.

How Lab-Grown Diamonds Are Graded and Certified: The Complete Guide

The four Cs—cut, color, clarity, and carat weight—are used to determine the overall grade of a lab-grown diamond. Lab-grown diamond cut refers to how well-proportioned and symmetrical the stone is; lab-grown diamond color indicates its hue or lack thereof; lab-grown diamond clarity measures inclusions or blemishes within the stone; and lab-grown diamond carat weight determines its weight (and thereby size). Combining these four factors gives each lab-grown diamond its unique appearance and value.

In addition to these four Cs, lab-grown diamonds are also graded according to their origin (mined vs. lab-grown) and growth method (CVD or HPHT). Lab-grown diamonds are chemically identical to mined ones but are much more affordable due to lower production costs associated with laboratory creation processes such as chemical vapor deposition (CVD) or high pressure/high temperature (HPHT). As such, many jewelers now offer lab-grown diamond options for customers looking for ethically sourced diamonds at competitive prices.

Diamond certificates provide detailed information about a particular lab diamond’s cut, color, clarity, carat weight, origin type (mined vs. lab-grown), growth method (CVD or HPHT), etc., allowing buyers to make an informed decision when shopping for jewelry pieces containing lab-grown diamonds.

Independent gemological laboratories issue these documents after thorough examination by experienced graders who specialize in evaluating precious stones like diamonds according to industry standards set forth by organizations like GIA – Gemological Institute Of America. In addition, a certificate typically includes photographs taken under magnification so that any imperfections can be clearly seen before purchase.

Finally, it is crucial for shoppers seeking ethically sourced lab diamonds from reputable sources to buy only from trusted retailers who guarantee authenticity with valid certification documents provided upon request before sale completion.

Diamond grading is a crucial part of the diamond industry, as it helps to ensure that lab-grown diamonds are accurately evaluated and certified. In addition, knowing the history behind diamond grading can help you make an informed decision when purchasing your lab-grown diamonds or jewelry.

In Summary: Lab-grown diamonds are graded according to the 4 Cs (cut, color, clarity, carat weight), origin type (mined vs. lab-grown), and growth method (CVD or HPHT). Certificates issued by independent gemological laboratories provide detailed information about a lab-grown diamond’s characteristics and should be requested from trusted retailers prior to purchase.

History of Diamond Grading

Diamond grading has been an integral part of the diamond industry since its inception in the early 20th century. The first standardized system for assessing diamonds was developed by GIA (Gemological Institute of America) in 1931 and is still used today. This system grades diamonds on four criteria: color, clarity, cut, and carat weight.

The development of this system was driven by a need to ensure that buyers were getting what they paid for when buying diamonds from different sources. A standard way to grade each diamond’s quality made it easier to compare prices across other vendors and ensure that buyers weren’t being taken advantage of.

How Lab-Grown Diamonds Are Graded and Certified: Diamond Example from Grown Brilliance
7.16 Carat Round Shaped Ideal Cut, F-Color, VVS2-Clarity, IGI Certified Lab Grown Diamond From Grown Brilliance

In recent years, the use of diamond grading has expanded beyond traditional mined stones to include lab-grown diamonds as well. Lab-grown diamonds are created using advanced technology in controlled environments where all aspects can be monitored and regulated more closely than with mined diamonds. As such, their quality can often exceed that of mined stones exposed to various environmental factors that can affect their appearance (color and clarity).

Lab-grown diamond grading systems consider additional factors not included in mined diamond evaluations, such as chemical composition and growth rate during production processes like HPHT (high-pressure, high-temperature) or CVD (chemical vapor deposition). These extra considerations help ensure buyers get precisely what they pay for when purchasing lab-grown diamonds instead of just relying on visual inspection alone, which may not always accurately reflect the actual value or quality of a particular stone due to its unique characteristics compared with traditionally sourced ones.

Diamond grading has come a long way over the years, and it is essential to understand this history when considering lab-grown diamonds. Next, we will examine how lab-grown diamonds are graded compared to mined diamonds.

In Summary: Lab-grown diamonds are graded and certified based on additional criteria such as chemical composition and growth rate, in addition to the traditional mined diamond grading system of color, clarity, cut, and carat weight. This helps ensure buyers get exactly what they pay for when purchasing lab-grown diamonds.

How Are Lab-Grown Diamonds Graded?

Lab-grown diamonds are graded using the same criteria as mined diamonds. This includes evaluating their color, clarity, cut, and carat weight. The grading process is conducted by a trained gemologist who uses specialized tools to measure the diamond’s characteristics.

The evaluation process is carried out by grading institutes such as GIA, IGI, and AGSL (see more about grading labs below). It involves analyzing multiple aspects, including proportions and angles measurement data points taken by experienced graders using advanced imaging technology combined with traditional methods used for decades by master jewelers around the globe today.

Finally, all these measurements are combined into what is known as “the 4Cs” – color, clarity, cut, and carat weight – which determine a lab-grown diamond’s quality grade and, ultimately, its price point depending on market conditions at any given time.

Lab-diamond color grading

The color of lab-grown diamonds is evaluated on a scale from D (colorless) to Z (light yellow). Colorless or near-colorless stones are considered more valuable than those with noticeable tints of yellow or brown. Learn more in our in-depth guide to lab-grown diamond colors.

How Lab-Grown Diamonds Are Graded and Certified: Color Grading Scales

Lab-diamond clarity grading

Clarity is assessed based on the number and size of inclusions present in the stone. Inclusions can be internal flaws such as tiny crystals or external blemishes like scratches and chips that affect its appearance and durability.

Lab-grown diamonds typically have fewer inclusions than mined ones due to their controlled growth environment, which makes them more useful for jewelry purposes. Read more in our detailed guide to lab-grown diamond clarity.

How Lab-Grown Diamonds Are Graded and Certified: Lab-grown diamond clarity example
Lab-grown diamond clarity grading by IGI. This example from James Allen

Lab-diamond cut grading

Diamond cut refers to how well the diamond has been shaped into its desired form. The cut determines how the diamond reflects light when viewed from different angles and affects its brilliance and sparkle, making diamonds so special.

A good cut will maximize these qualities, while an inferior one will minimize them, reducing overall value significantly. Therefore, we always recommend choosing only the highest lab-grown diamond cut grades. Learn about lab-grown diamond cut and why it’s so important.

Lab-diamond carat grading

Carat weight measures a diamond’s size relative to other stones; larger stones are more expensive because they require more raw material during production. However, this isn’t always true since some cuts may require less material even though they weigh heavier than others due to their shape. Learn more in our guide to lab-grown diamond shapes. Learn about lab-grown diamond carats.

Grading Fancy-Shaped Lab-Grown Diamonds

When grading fancy-shaped diamonds (also referred to as fancy-cut), the process is slightly different than for brilliant round cuts. Fancy-shaped diamonds are graded on their symmetry, polish and proportioning compared to the standard ideal of a brilliant round diamond.

How Lab-Grown Diamonds Are Graded and Certified: Grading of lab-grown fancy diamonds
Fancy-shaped lab-grown diamond. Example from James Allen.

Lab-grown diamond symmetry

The symmetry grade of a fancy-shaped diamond refers to how well-proportioned the facets are when compared. Symmetry grades range from Excellent (EX), Very Good (VG), Good (G), Fair (F), to Poor (P).

A VG or G rating is considered acceptable for many shapes, while an EX rating is preferred by some buyers who want maximum brilliance and fire from their diamond. Generally, we recommend an EX rating if possible and prioritizing diamond cut. However, in some cases, a VG cut can be acceptable.

Lab-grown diamond polish

The polish grade of a fancy-shaped diamond refers to how smooth its surface appears under magnification. Polish grades range similarly from Excellent (EX) to Poor (P). An EX or VG rating will produce maximum sparkle, while lower ratings may result in less brilliance and fire due to imperfections on the surface of the stone.

Lab-grown diamond proportioning

The proportioning grade of a fancy-shaped diamond refers to how closely it adheres to the ideal proportions set out by gemologists as being “ideal” or “very good” quality standards.

Proportioning grades range from Ideal (IDE) and Excellent (EX) to Poor. IDE or EX ratings mean that all angles, depths, and table sizes meet exact specifications set out by gemologists; these stones will usually have more sparkle than those with lower ratings, such as VG or G, which may have slight variations in angle size that can affect overall performance.

Grading Fancy-Colored Lab-Grown Diamonds

Because fancy-colored lab-grown diamonds are exactly the same as mined diamonds, apart from the source, they are also graded according to the same standards as mined diamonds. This ensures you can compare lab-grown and mined diamonds and buy with confidence.

However, fancy-colored diamonds are graded differently than colorless diamonds (white diamonds). The Gemological Institute of America (GIA) is the most widely recognized grading institute for fancy-colored diamonds. They use a system called “The GIA Color Grading Scale” to evaluate them.

This scale has nine grades ranging from Faint to Fancy Vivid:

Faint-colored lab-grown diamonds

These are very light in tone and saturation, making them difficult to see even with magnification. They have little value compared to other colored diamonds.

Very light-colored lab-grown diamonds

Slightly more intense than faint but still quite pale in appearance.

Light-colored lab-grown diamonds

With a visible hue but low intensity, these stones can appear washed out or grayish when viewed without magnification.

Fancy light-colored lab-grown diamonds

A noticeable hue that is slightly stronger than light grade stones; usually used for smaller stones such as melee sizes or accent pieces in jewelry designs where size matters more than color intensity does.

Fancy-colored lab-grown diamonds

A noticeable level of color saturation that stands out against white backgrounds; is often used for larger stones, such as centerpieces in engagement rings or statement necklaces and earrings, due to their higher value compared to lighter colors at this price point range.

Fancy intense or fancy vivid

Highly saturated hues that stand out even on darker backgrounds; are typically reserved for high-end jewelry pieces because of their rarity and desirability among collectors and connoisseurs alike who appreciate vibrant colors over subtle ones when it comes to luxury items like diamond jewelry.

In Summary: Lab-grown diamonds are graded using the same criteria as mined diamonds, known as the 4Cs – color, clarity, cut, and carat weight. A trained gemologist conducts this process to determine its quality grade and, ultimately, its price point.

Next, let’s look at what diamond certificates are and how they help guarantee quality.

What Are Lab-Grown Diamond Certificates?

Diamond certificates are documents issued by a gemological laboratory that provide an assessment of the quality and characteristics of a diamond. They are also known as diamond grading reports, diamond identification reports, or simply “diamond certificates”.

A certificate is important for buyers to understand because it provides detailed information about the lab-grown diamond’s physical properties, such as its cut, clarity, color grade, carat weight, and measurements.

It also contains a diagram showing the exact proportions of the lab-grown diamond, along with any additional comments from the grader regarding inclusions or other features. This information can be used to compare different stones and make sure you’re getting what you pay for when shopping for lab-grown diamonds.

The most common type of certificate is issued by one of the major international gemological laboratories: GIA (Gemological Institute of America), IGI (International Gemological Institute), Gem Certification & Assurance Lab (GCAL), and American Gem Society Laboratories (AGSL).

The diamond laboratories all employ strict criteria to evaluate diamonds according to their 4Cs – Cut, Clarity, Color, and Carat Weight – which helps buyers identify high-quality stones at competitive prices.

How Lab-Grown Diamonds Are Graded and Certified: Lab-grown diamond certificate from IGI
A lab-grown diamond certificate from IGI. This example was readily available for download at James Allen

In addition to providing objective evaluations of each stone’s unique qualities, certificates also help protect consumers against fraud since they contain serial numbers matching with specific lab-grown diamonds, so they can be tracked if needed. Furthermore, many retailers will only accept certified diamonds to guarantee authenticity and ensure customer satisfaction with their purchase.

When buying lab-grown diamonds online, it is critical to ask for certification before making your purchase, as this document will provide all the necessary details about your chosen diamond(s).

You should always check that certificates come from GIA, IGI, AGSL, or GCAL, as these are considered industry standards when evaluating both mined and lab-grown diamonds (GIA mainly grades mined diamonds, while IGI grades most lab-grown diamonds).

Diamond certificates are an important part of buying diamonds, whether lab-grown or mined. Knowing who grades them and what information is included in the certificate will help you make an informed purchase decision when shopping for lab-grown diamonds.

In Summary: Lab-grown diamonds should always be certified by reputable diamond laboratories such as GIA or IGI in order to guarantee authenticity and ensure customer satisfaction. Certificates provide detailed information about the stone’s physical properties, such as its cut, clarity, color grade, carat weight, and measurements. They also contain a serial number for tracking purposes.

Who Grades Lab-Grown Diamonds?

Lab-grown diamonds are becoming increasingly popular as an alternative to mined diamonds. As such, there is a need for reliable and accurate grading of these stones. The organizations that grade lab-grown diamonds have different standards and processes in place to ensure the quality of each stone.

The Gemological Institute of America

The Gemological Institute of America (GIA) is one of the world’s most respected diamond grading laboratories. They offer two separate reports for lab-grown diamonds: a Diamond Grading Report and a Laboratory-Grown Diamond Identification Report. The GIA evaluates lab-grown diamonds based on their cut, color, clarity, carat weight, fluorescence, symmetry, and polish using their standard criteria for mined diamonds.

The International Gemological Institute

The International Gemological Institute (IGI) also offers diamond certification services for both mined and lab-grown diamonds. IGI uses its own set of parameters when evaluating lab-grown diamonds, which includes assessing the cut grade; color grade; clarity grade; carat weight; measurements; fluorescence intensity/color; inscription(s); laser drilling or filling treatments if any exist etc.

The biggest difference compared to the grading of GIA is that the highest lab-grown diamond cut grade at IGI is ideal, while GIA’s is excellent. So, if IGI graded the lab-grown diamonds you are comparing, only choose one with the ideal cut grade.

American Gem Society Laboratories

Another organization that grades lab-grown diamonds is American Gem Society Laboratories (AGSL), a grading laboratory majority-owned by AGS (and thus AGSL is sometimes referred to, incorrectly, as AGS). AGSL provides comprehensive reports with detailed information about each diamond’s cut, color, clarity, and carat weight, along with other important factors like symmetry or polish level, etc. Unlike IGI and GIA, AGSL uses a 0-10 point system, which, arguably, makes more sense. See how the AGS scale compares with the traditional GIA scale.

The Gem Certification & Assurance Lab

The Gem Certification & Assurance Lab (GCAL) is a more recent diamond laboratory that has become the second-most famous institute for lab-grown diamonds. GCAL is unique for its diamond certificate guarantee, which provides consumers and diamond traders with guaranteed diamond grading. You’ll find GCAL lab-certified diamonds and IGI-certified lab diamonds, both reputable and trustworthy diamond laboratories.

European Gemological Laboratory

Finally, there are independent gem labs like the European Gemological Laboratory (EGL), which specialize in certifying loose, colored gems, including fancy-colored sapphires and some laboratory-created non-diamond gems such as moissanite, in addition to diamond-grading. Broadly speaking, diamonds certified by EGL tend to be more loosely graded, and EGL is not as widely recognized as GIA, AGS(L), and IGI.

Jeweler grading

Lab-grown diamond jewelers sometimes grade their own diamonds and do not use independent laboratories such as the above. The lab-grown diamond jewelers include Vrai, who source their diamonds from Diamond Foundry (their owner) and grade diamonds internally. Learn why that is a problem in our review of Vrai.

Lightbox Jewelry is another example of a lab-grown diamond seller who grades their own diamonds. This is one of many reasons we do not recommend them, as you can read in our review of Lightbox Jewelry.

Lastly, it’s common for jewelers to grade small diamonds themselves since independent labs do not grade these, or it’s too expensive relative to their value. These diamonds are often used as accent stones, but their quality still matters. That is why it’s critical to buy lab-grown diamonds only from our highest-rated diamond sellers (see the list of recommended jewelers at the bottom of this guide).

In Summary: Lab-grown diamonds can be graded and certified by organizations such as the GIA, IGI, and AGSL. These organizations evaluate lab-grown diamonds based on their cut, color, clarity, carat weight, fluorescence, symmetry, and polish using strict and standardized criteria. Reports from these diamond labs help customers compare different diamond options before making a purchase decision.

FAQs about How Lab-Grown Diamonds Are Graded and Certified?

Do lab-grown diamonds get certified?

Yes, lab-grown diamonds get certified. The Gemological Institute of America (GIA) and the International Gemological Institute (IGI) are two leading gemology laboratories that offer certification for lab-grown diamonds. They certify the lab-grown diamond 4Cs – carat weight, color grade, clarity grade, and cut grade – as well as issue a report on the diamond’s origin. IGI also provides certification for lab-grown diamonds with detailed information about their quality characteristics. Both organizations use advanced technology to ensure accuracy in their grading process. Other grading institutes that grade lab-grown diamonds include the American Gemological Society Laboratory (AGS) and the European Gemological Laboratory (EGL).

What are the grades of lab-grown diamonds?

Lab-grown diamonds are graded using the same 4C’s (Cut, Color, Clarity, and Carat) as mined diamonds.
  • Cut refers to the diamond’s proportions and symmetry. Diamond cut ranges from poor (worst) to excellent (best) if graded by GIA or ideal (best) if graded by IGI. 
  • Color is based on its hue and saturation. For example, lab-grown diamonds range from D (colorless) to Z (light yellow).
  • Clarity is determined by the presence of inclusions or blemishes. The highest clarity grades for lab-grown diamonds are Internally Flawless (IF), Very Very Slightly Included 1 & 2 (VVS1/VVS2), and Very Slightly Included 1 & 2 (VS1/VS2).
  • Carat weight is an indirect measure of size. One carat is equal to 0.2 grams or 0.007 ounces.

Which diamond lab certification is best for lab-grown diamonds?

The most popular diamond lab certification for lab-grown diamonds is the International Gemological Institute (IGI). IGI is a leading authority in the field of gemology and provides comprehensive grading reports that include an analysis of carat weight, color, clarity, cut grade, polish, and symmetry. With its rigorous standards and extensive expertise in diamond grading, IGI is widely considered one of the most reliable sources for determining quality in lab-grown diamonds.

Which is better for lab-grown diamond grading and certification, GIA or IGI?

Both the Gemological Institute of America (GIA) and the International Gemological Institute (IGI) are respected organizations in the diamond industry. Both offer reliable grading reports for diamonds. GIA is considered more widely accepted and trusted by consumers due to its long history and for being the inventor of the diamond 4 Cs.

GIA has a well-established reputation as an independent authority on gemstone quality. At the same time, IGI is known for its expansive network of laboratories worldwide that provide certification services. IGI is the leading grading institute for lab-grown diamonds, while GIA is for mined diamonds.


Lab-grown diamonds undergo a rigorous evaluation process by experienced gemologists to determine their quality and value. Diamond certificates provide assurance that your diamond is authentic and accurately graded. With these documents, you can be sure that when you purchase a lab-grown diamond, it has been appropriately graded and certified according to industry standards, mainly if done by IGI or GIA.

Are you looking to buy lab-grown diamonds and diamond jewelry but don’t know where to start? With LabGrownCarats, you can find all the information and resources necessary for a successful purchase.

Where to find lab-grown diamonds with diamond certificates?

Where to buy lab-grown diamonds with diamond certificates?

When shopping for lab-grown diamonds, you must make sure you buy from a reputable source. One way to ensure the quality of your purchase is by looking for diamond certificates.

A diamond certificate is an official document issued by a recognized gemological laboratory that provides details about the specific characteristics of a particular stone. It includes information such as cut, clarity, color, and carat weight.

All leading lab-grown diamond jewelers will provide you with a lab diamond certificate before purchase. Ideally, they should be accessible on the website or by contacting customer support. Do not buy from them if they are unwilling to provide the certificate.

We review lab-grown diamond jewelers and determine the best places to buy lab-grown diamonds.

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Rolf Hartmann
Rolf Hartmann

Rolf Hartmann has decades of experience in the jewelry industry. He knows everything you need to know to find the perfect diamond. He's an expert in lab-grown diamonds and has followed the exciting development of lab diamonds from industrial usage to the incredible gemstone quality that lab-grown diamonds are today. Rolf guides you to find the right diamond at the best possible price and expertly and transparently reviews all lab-grown diamond sellers.

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