What is IGI Diamond Certification?

by Willyou.net * Jun 2, 2021

For anyone looking to buy a diamond for the first, second or fiftieth time, a comprehensive and reliable grading report is essential. We often talk exclusively about GIA graded diamonds, but glossing over the fact that there are other institutions offering their own methodologies for assessing the quality of diamonds can be confusing.

You may, for instance, have come across IGI diamonds during your research. The IGI (or the International Gemological Institute) is the largest independent gemological laboratory in the world. Established in 1975, it has locations in all major diamond trade cities.

An IGI diamond certification (grading report) evaluates the diamond on its quality and structure as well as the 4 C’s: cut, clarity, color, and carat according to international standards.

The History of IGI Diamond Certification

The International Gemological Institute, ISI, was established in 1975 in Antwerp, Belgium. After GIA, they are the 2nd most well-known lab in the world, grading a significant number of diamonds each and every year. They are, however, better more widely known outside the United States, and especially popular in the Asian region.

Is IGI Reputable for Diamonds?

Yes, it is a highly reputable institution recognized around the world.

That said, it is not considered to be among the very best labs for grading diamonds. We will explain why in greater detail below but, for now, let’s talk you through the specifics for the IGI’s grading scales for each of the Four Cs.

IGI Certification Grading Scale

Like many of the most popular methods for grading diamonds, the IGI’s diamond grading system is categorized by 4 C’s: carat, color, clarity, and cut: 


The carat scale for IGI diamond certification depends on the size and weight ratio. IGI does not include larger gems if the weight does not match the size in their IGI certification, due to the fact that it isn’t considered “perfect”.


IGI grades the color of a diamond on the same grading scale as the GIA’s widely-used grading scale – a letter color scale ranging from D – Z. As always, the less color a diamond has, the higher the value it has. A diamond graded with the letter D represents a colorless diamond and continues up the scale to a diamond with the letter Z, representing a light yellow or brownish tint.


Much like the GIA, the IGI grades clarity on how clean a diamond is from inclusions and blemishes. The diamond’s size, number, location, and nature of internal inclusions are aspects that are inspected during the clarity assessment.

But, while the GIA utilizes a clarity scale ranging from FL to I2, the IGI’s clarity scale runs from 0-10, with a score of 0 being completely flawless up to a score of 10 which includes significant flaws.


IGI grades the cut of the diamond on the standard cut-based scale, based on its proportion, angles and symmetry:

  • Ideal
  • Excellent
  • Very Good
  • Good
  • Fair
  • Poor

IGI Diamond Grading Chart

IGI diamond certification reports are provided for diamonds of any size and can be customized for a variety of customers throughout the diamond industry. The grading report provides a complete assessment of the stone’s 4 C’s: color, clarity, carat and cut. The report also includes a plotted diagram of the characteristics and proportions of each diamond as well as information about the cut by analyzing proportions, polish, and symmetry.

IGI also issues an IGI Diamond ID which is a passport-sized document containing the same information as the grading report, just without the plotted diagram.

IGI certificate diamond
IGI diamond certificate

Advantages & Disadvantages of an IGI Diamond Certification

There are both advantages and disadvantages that come with an IGI diamond certification. Advantages include lower costs of certification, and a faster turnaround time than what is offered by other high profile diamond grading institutions.

The disadvantage of an IGI diamond certification includes inconsistency, as reports are pumped out at a faster pace than other grading labs. This leads to much looser and less predictable results – a major downside to anyone looking to make the strongest investment possible into their diamond.

Are IGI Diamonds Better than GIA Diamonds?

No – the GIA’s methods for assessing diamonds are far more reliable, even if they are slower and more costly.

IGI diamonds cost less than GIA diamonds because of the fact that the process of grading each of the stones attributes takes less time. And, while skimping on time will save you money in the short-term, it really isn’t a sacrifice you want to make on something this important.

Think of it this way. If your jeweler told you they could spend one day making a ring setting for you – that’s everything from the design to the creation itself – or, at a higher upfront cost, spend a couple weeks making sure every small detail was perfected, and every component handmade, you know which one you’d go for.

Why? Because, alongside the diamond and the gold, platinum and silver, time is yet another factor that is essential to creating a beautiful ring.

The additional time the GIA invests into grading diamonds translates into greater consistency, and much more attention to detail – and the reason why we consider their approach to be a clear winner.

So, Should You Buy an IGI Diamond?

Ideally, no. GIA diamonds represent the safest investment for any shopper.

For a total beginner, it’s easy to imagine that all reputable diamond labs will offer the same level of assurance over the value of a diamond. In reality, the different methodologies and labels offered by these institutions can ‘muddy the waters’, and confuse first-time shoppers over what it is that they’re buying.

This is another reason why we focus on the GIA’s methods. In addition to offering the greatest level of consistency – and, of course, more time and attention that some of the other labs are able to give to their diamonds – focusing on the GIA’s scales gives shoppers the clarity they need to know what they are paying for, and how valuable it really is.