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IGI vs. GIA Certifications: Which is Best?

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A diamond is often an expensive purchase, so confidence in the one you select is crucial. 

While many rely on a trusted brand name in determining whether it’s a quality diamond, what’s more important is a certification from a reliable organization.

The International Gemological Institute (IGI) and the Gemological Institute of America (GIA) are two of the most popular grading institutions that verify the characteristics of a diamond.

Let’s compare the IGI versus GIA so you’ll learn which is best for you.

What are IGI Diamond Certifications?

IGI Diamond Assessment

The IGI is one of the largest independent gem labs in the world. It was founded in 1975 and is headquartered in Antwerp, Belgium.

Its location places it in proximity to many of the mines where diamonds are sourced. 

Their certifications are common in Europe and Asia. In the United States, it found a market serving jewelry retailers like Jared, Kay, and Zales.

By offering low prices for grading reports and fast turnaround times, they formed productive partnerships with these vendors.

In addition to diamond certifications, the IGI also conducts research on gems and provides education to the industry.

If you’re exploring an IGI diamond, ask the retailer for its report number. You can verify the IGI report on its website here.

IGI diamond certifications have a similar format as ones from other institutions such as the HRD, GCAL, or the GSI.

IGI Diamond Certificate

At the top of the report, it identifies the diamond as lab-grown or natural, including its:

  • Proportions
  • Shape and cutting style
  • Measurements

The traits that most affect a diamond’s value are the four Cs of color, cut, carat weight, and clarity. IGI reports have a section dedicated to these qualities.

Four Cs on IGI Report

To help buyers who aren’t familiar with where those grades fall along the spectrum, the reports include a scale. For example, the IGI diamonds are graded on a scale of flawless to I3 clarity.

You can view where the diamond’s clarity grade falls along that scale.

The same is true of color. The scale shows “colorless” diamonds are graded D-F, and the spectrum continues to S-Z for “light” colored diamonds.

The “Additional Grading Information” section details the other important traits.

Combined with the clarity characteristics plot in the bottom left, it gives you the complete picture of what you need to know about the diamond.

IGI also provides certifications for colored diamonds.

IGI Colored Diamond Report

They follow a similar process by first determining its origin and whether it has any artificial treatments.

The report has many similarities compared to ones for natural diamonds, but they often include an image so you’ll know its color shade.

What are GIA Diamond Certifications?

The GIA is the preeminent institution for evaluating the quality of diamonds. Founded in 1931, it’s a nonprofit known for research on gems and reports on natural diamonds.

It also provides assessments on:

  • Laboratory-grown diamonds
  • Colored stones
  • What material makes up a stone

Many of the most popular online diamond vendors, such as James Allen and Blue Nile, have their diamonds certified by the GIA. Lumera promotes how they only sell GIA diamonds.

Grading a diamond along the four Cs is universal, but the GIA developed these standards. 

When a diamond is sent to be graded by the GIA, they first determine whether it’s natural or lab-grown.

Along with evaluating the diamond across the four Cs, they check for any clarity-enhancement procedures that attempt to cover up inclusions.

They consolidate these notes and more into a report that looks similar to one from the IGI.

GIA Report for Marquise Cut

At the top of a GIA diamond certificate is the report number. If you know the report number of a diamond you’re considering, you can verify the report on the GIA’s website here.

You read GIA and IGI diamond certifications in a similar way.

The “Grading Results” section details its clarity, cut, color, and carat weight. The section below notes its polish, symmetry, and fluorescence, including additional notes about inclusions.

For a complete picture of the flaws on a GIA diamond, examine both the inclusion plot at the bottom of the certificate and the comments to the left.

Like the IGI, the GIA certifies colored diamonds. This sample report from the GIA for a pear-cut, fancy blue diamond includes an image at the top so the buyer knows its color.

GIA Report on Colored Diamond

While the report still includes familiar sections like the inclusion plot and four Cs, it also shows how they determine color using the GIA colored diamond scale.

What are the Differences Between the IGI and GIA?

All diamond certifications aren’t created equal. Its value is in the reliability of the grading institution and whether they properly assess its traits.

Here are the differences in what you can expect between an IGI and GIA diamond certification.

GIA’s Grading Standards are Considered More Rigorous

The GIA’s standards are known as the most rigorous compared to other grading institutions, including the IGI. 

Jewelry Insurance Issues notes the AGS and GIA are considered the most reliable.

In a well-known study, Rapaport sent diamonds to several of the leading grading labs and found the GIA as the most strict lab, followed by the IGI.

Strict criteria are generally in the interest of the buyer but not always the seller.

This is because a diamond with higher grades on the report often sells for a higher price.

As a rule of thumb, you can expect the IGI to grade a diamond one or two grades higher than the GIA in categories like color and clarity.

For example, if the GIA decides a diamond has an H color and VS1 clarity, the IGI may give it an G color and VVS2 clarity.

Or if the GIA grades its cut as “good”, the IGI may determine it’s “very good.”

GIA Diamond with Good Cut

In other cases, there may be a difference across only one or two of these traits.

In fact, the team at The Diamond Pro tested this as well and found this to be the result in many cases.

It’s not because the IGI is intentionally applying loose standards. There are no objective standards for where a diamond’s clarity, cut, and color land on the scale.

Expert gemologists at the IGI and GIA compare the diamond to a given standard and decide where it lands. If its color is closest to the standard used as a J color, they’ll designate it the same.

Some claim the IGI’s United States locations are more reliable and rigorous than international ones. 

The problem with this claim is the U.S. locations can honor the evaluation from international graders instead of taking an objective look. 

On the other hand, the GIA ignores any markings or other assessments and instead gives it a fresh examination.

Regardless of whether the GIA or IGI certifies a diamond, the carat weight is objective. 

You shouldn’t expect any difference in the carat weight no matter which lab grades it.

IGI Specializes in Lab-Grown Diamond Reports

While the IGI isn’t known to be as reliable as the GIA in certifying natural diamonds, it’s more respected by the industry for its reports on lab-grown diamonds.

In fact, many of the lab-grown diamonds at popular retailers like James Allen are certified by the IGI.

One reason they’re regarded for these reports is because the IGI was the first major organization to certify the color and cut of lab-grown diamonds.

IGI reports for lab-grown diamonds are nearly identical to the reports for natural ones, but they’re yellow. 

IGI Certificate for Lab-Grown Diamond

The girdle is also inscribed with the serial number and the words “lab-grown”.

The GIA also provides certifications for lab-grown diamonds, but they aren’t as popular as the ones for natural diamonds. 

The report also looks similar compared to one for a natural diamond and features most of the same information.

In the comments section, it states the process by which the diamond was created.

You’ll see similar comments on IGI certifications for lab-grown diamonds.

While we recommend GIA certifications for natural diamonds, an IGI report is sufficient for a lab-grown one.

IGI Provides Appraisals

There’s a difference between a diamond certification and appraisal. A certification focuses on describing the qualities of a diamond such as its:

  • Carat weight
  • Symmetry
  • Polish
  • Inclusions

An appraisal, on the other hand, seeks to determine its monetary value.

The GIA doesn’t provide appraisals. In fact, the organization says it’s not involved in jewelry pricing in any way. 

This prevents any conflict of interest, where the GIA could have incentive to inflate the grade of a diamond and cause it to be appraised at a higher value.

As a research and educational institution, its goal is to provide objective analysis of gems instead of determining how much they’re worth.

But the IGI does assess the value of a diamond. They’ve partnered with several third-party diamond appraisers and even have co-branded reports.

IGI Diamond Certificate with Appraisal

The reason they provide this service is many jewelry insurers require appraisals from another organization for high-value pieces.

We recommend not receiving an appraisal from the organization that certified it. Instead, choose one from this list of the GIA’s recommended appraisers.

How Does the Certificate Affect a Diamond’s Price?

The name of the organization at the top of a diamond certificate affects a diamond’s price in multiple ways.

The first is that if a diamond is graded as higher quality, it will often sell for a higher price.

For example, if all else is equal, a diamond with VVS1 clarity will sell for more than one with VVS2 clarity.

Let’s look at how the exact clarity grade impacts the price of diamonds from James Allen by looking at ones with the following qualities:

  • Carat weight: 1.05
  • Color: H
  • Clarity: VVS2
  • Cut: Excellent

There are two available, both priced at $2,870.

VVS2 Clarity Diamonds

For the same quality diamond, except with a VVS1 clarity grade, is priced at $3,300.

That’s a 15 percent increase because of one grade higher on the clarity scale.

This means more rigorous grading often results in a lower price for the buyer.

The second way a grading certificate impacts the price of a diamond is vendors charge a higher price for diamonds assessed by the GIA versus IGI. 

GIA reports cost retailers more because of their strong reputation, and they know buyers are willing to pay more for a diamond graded by the GIA compared to other organizations.

Diamonds from James Allen provide another helpful example of this idea.

We examined diamonds with the following grades:

  • Carat: 1.00
  • Color: G
  • Cut: Very good
  • Clarity: VS1

Then we filtered them by GIA versus IGI certificates.

The price range for GIA diamonds is $5,290-$11,330.

For IGI diamonds, it’s $5,520-$5,680.

Diamonds Graded by IGI

This shows the premium that sellers charge for a GIA diamond.

Should You Buy an IGI or GIA Diamond?

We recommend you buy a diamond certified by the GIA versus IGI unless it’s lab-grown. In that case, both certifications are sufficient.

The GIA is widely considered the most consistent diamond grading institution, and it’s important you have confidence in the quality of the assessment. 

You’ll pay a premium for a GIA report compared to ones from other labs, but it’s worth the extra cost.

While there are jewelry retailers with better reputations than others, you should determine the quality of a diamond based on a reliable certificate, not only the brand name of the seller.

Devon Tyler

Devon Tyler

Devon Tyler is the founder of TeachJewelry.com.

He earned an Applied Jewelry Professional Diploma from the Gemological Institute of America and now brings you essential information about diamonds, settings, and more.

Devon has consulted with leading jewelry brands, and his work has been cited in Diamond Nexus and other industry publications.

He's also a member of the International Gem Society.

Devon enjoys discussing jewelry with readers, so contact him with any questions at tyler.devon@teachjewelry.com.

Learn More About Devon

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