When shopping for certified lab grown diamonds, one of the most common questions buyers ask is whether IGI is a reliable grading authority. The short answer is yes. IGI is widely considered one of the leading certification labs for lab grown diamonds and is trusted by many major retailers, manufacturers, and buyers worldwide.
However, understanding why IGI is popular, how its grading compares to other labs, and how to verify an IGI certificate can help you make a smarter buying decision.
In this guide, we explain what IGI certification means, how accurate it is for lab grown diamonds, and what to look for before purchasing a certified stone.
(Related: Do Lab Grown Diamonds Come With Certificates?)
What Is IGI?
International Gemological Institute, commonly known as IGI, is one of the largest independent diamond grading laboratories in the world. The organization grades both natural and lab grown diamonds and issues detailed certification reports describing a diamond’s characteristics.
An IGI report typically evaluates:
- Cut quality
- Carat weight
- Colour grade
- Clarity grade
- Polish and symmetry
- Fluorescence
- Measurements
- Growth method for lab diamonds
For lab grown diamonds specifically, IGI has become one of the most commonly used certification labs in the market.
(Related: What Is a Certified Lab Grown Diamond?)
Why IGI Is Popular for Lab Grown Diamonds
IGI gained strong recognition in the lab grown diamond industry earlier than many competing laboratories. As lab diamonds became more mainstream, IGI invested heavily in grading technology and standardized reporting for man made stones.
Today, many online diamond retailers and wholesalers prefer IGI certification because:
- IGI grades a high volume of lab grown diamonds
- Reports are widely recognized internationally
- Certification turnaround times are efficient
- The grading format is easy for buyers to understand
- IGI reports include detailed lab grown identification
For buyers comparing certified lab grown diamonds, IGI reports provide enough information to evaluate quality and value confidently.
(Related: How Do I Know if I Am Overpaying for a Lab Diamond?)
Is IGI Accurate for Lab Grown Diamonds?
In most cases, yes. IGI is generally considered reliable and consistent for lab grown diamond grading.
That said, some industry professionals believe IGI grading can occasionally be slightly softer than certain other laboratories, particularly when compared to Gemological Institute of America, often referred to as GIA.
This does not mean IGI certificates are inaccurate. It simply means that grading standards between laboratories may vary slightly.
For example:
- An IGI VS1 clarity diamond might receive a VS2 grade elsewhere
- A colour grade could differ by one level depending on the lab
These small differences are common across the diamond industry and are not unique to IGI.
For most buyers, especially those purchasing lab grown diamonds online, IGI certification remains a trusted and practical choice.
(Related: How Do I Compare Lab Diamond Prices?)
IGI vs GIA for Lab Grown Diamonds
One of the biggest comparisons buyers make is between IGI and GIA certification.
IGI Advantages
IGI is often preferred for lab grown diamonds because:
- More lab grown inventory is IGI certified
- Reports are detailed and buyer friendly
- Certification costs are often lower
- The lab has extensive experience with man made diamonds
GIA Advantages
GIA is traditionally viewed as the strictest grading authority in the diamond industry.
Some buyers choose GIA because:
- The brand has strong global recognition
- Grading standards are perceived as extremely conservative
- High value diamonds often carry GIA reports
Which Is Better?
For lab grown diamonds specifically, IGI is usually more than sufficient for most buyers.
If you are purchasing a very expensive or investment-focused stone, you may prefer GIA for additional confidence. However, for everyday engagement rings and fine jewellery, IGI certified lab grown diamonds offer excellent value and credibility.
(Related: What Is the Best Value Lab Diamond Specification?)
What Information Does an IGI Certificate Include?
Understanding how to read an IGI certificate helps you compare diamonds more effectively.
A typical IGI lab grown diamond report includes several key sections.
Diamond Identification
The report confirms that the stone is laboratory grown rather than natural.
It may also specify whether the diamond was created using:
- CVD (Chemical Vapor Deposition)
- HPHT (High Pressure High Temperature)
The 4Cs
The certificate grades the traditional diamond quality factors:
Cut
Cut quality affects brilliance and sparkle more than any other factor.
Excellent or Ideal cut grades are typically the best choice for maximum light performance.
Colour
Lab diamonds are graded on the same colour scale as natural diamonds.
The scale usually ranges from D to Z.
Near colourless grades such as G, H, and I often provide the best value.
Clarity
Clarity measures internal inclusions and external blemishes.
VS1 and VS2 clarity grades are popular because they often appear eye clean without the premium pricing of flawless stones.
Carat Weight
Carat measures the diamond’s weight and influences size and price.
Additional Quality Details
IGI reports also include:
- Table percentage
- Depth percentage
- Fluorescence
- Polish
- Symmetry
- Measurements
- Laser inscription details
These details help buyers assess cut precision and overall craftsmanship.
(Related: Should I Spend More on Carat, Colour, Clarity, or Cut?)
How to Verify an IGI Certificate
Before purchasing any certified lab grown diamond, you should verify the report.
You can usually do this by:
- Checking the report number on the IGI website
- Matching the laser inscription on the diamond girdle
- Reviewing the grading details carefully
- Confirming the report format and security features
Verification helps ensure the certificate is genuine and matches the actual diamond being sold.
(Related: Is It Worth Paying More for Better Cut?)
Are IGI Certified Lab Diamonds Good Value?
In many cases, yes.
IGI certified lab grown diamonds often provide excellent value because:
- Lab diamonds already cost less than natural diamonds
- IGI certification is widely accepted in the market
- Buyers can compare quality transparently
- Pricing is easier to evaluate using certification data
For shoppers focused on appearance, size, and overall beauty rather than resale prestige, IGI certified diamonds are often a smart purchase.
(Related: Is It Worth Paying More for Better Clarity?)
What to Watch Out for When Buying IGI Lab Diamonds
Even with certification, not all diamonds offer equal value.
A certificate confirms grading information, but it does not automatically guarantee that a diamond is well priced or visually impressive.
Here are some important considerations.
Do Not Focus Only on Carat Size
Large diamonds with poor cut quality may appear dull or lifeless.
A smaller, well cut diamond often looks brighter and more attractive.
If you are unsure how different quality factors affect pricing, reviewing a guide on how to compare lab diamond prices can help you identify stronger overall value choices.
Compare Multiple Diamonds
Two diamonds with the same grades can still look different in real life.
Always compare:
- Cut proportions
- Videos or high resolution imagery
- Certification details
- Overall visual appeal
Understand Clarity Practicality
Higher clarity does not always produce a visible difference.
Many VS clarity diamonds look identical to higher grades without the extra cost.
Learning more about the best value lab diamond specification can help buyers balance appearance and budget more effectively.
Verify Certification Authenticity
Always confirm that the IGI report matches the diamond you are buying.
Reputable sellers should provide:
- Full certificate access
- Clear diamond imagery
- Report verification information
(Related: Is It Worth Paying More for Better Colour?)
Should You Buy an IGI Certified Lab Grown Diamond?
For most buyers, the answer is yes.
IGI certified lab grown diamonds are widely trusted, professionally graded, and commonly sold by reputable retailers around the world.
They offer:
- Reliable grading information
- Transparent quality evaluation
- Strong value for money
- Broad market acceptance
The key is not simply choosing an IGI certified diamond, but selecting one with strong overall proportions, excellent cut quality, and fair pricing.
A certificate should support your decision, not replace careful comparison.
(Related: When Is a Lab Diamond Too Cheap?)
Final Thoughts
IGI is considered a good and reliable certification lab for lab grown diamonds. Its reports provide detailed grading information that helps buyers compare stones with greater confidence and transparency.
While some buyers prefer GIA for stricter grading reputation, IGI remains one of the most respected and widely used certification authorities for lab grown diamonds today.
The best approach is to use the certificate as one part of the buying process while also evaluating cut quality, visual appearance, and overall value. A well chosen IGI certified lab grown diamond can offer exceptional beauty and pricing without sacrificing credibility.