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This is a widely debated topic with numerous articles floating around on the internet about the differences between IGI, GIA & AGS diamond certifications. While there is a general consensus on the superiority of labs, what we would like to address in this article is specifically in relation to lab grown diamonds.

We have drawn up a little summary below on what the various certifications bring to the table. But before we get to that, why do we even need to certify our diamonds? Unfortunately, in a world where trust is a scarce commodity, we would like to feel secure when buying something as expensive as a diamond. Having it graded and certified proves that it is indeed a real diamond, and not a diamond simulant or substitute. This is even more important now with the popularity of lab grown diamonds; buyers of natural diamonds would not want to unknowingly pay natural diamond prices for a lab grown diamond especially given how impossible it is to tell the two apart without the right equipment.

However, apart from verifying the authenticity of your diamond, there might not be an actual need to grade a diamond’s 4Cs (Carat, Colour, Clarity, Cut) for most diamonds as much of the minute grading differences is indiscernible to the naked eye. This grading system would be more applicable for investment grade diamonds where you’d want to know exactly how colourless and flawless your diamonds are. However, the invention of the 4Cs has done a great job at marketing diamonds, allowing for a more diverse and profitable pricing system, where the marginally higher quality diamonds can fetch a much larger premium. Which is why we try to advise our clients on the most value for money diamonds without having to splurge on a D Flawless diamond.

GIA - Gemological Institute of America

“GIA is a charitable, non-profit organization with a mission to ensure the public trust in gems and jewelry by upholding the highest standards of integrity, academics, science, and professionalism.”

They are perhaps the most well known and recognised certifying body in the world. They have set an extremely high standard for diamond certification and are the benchmark for other labs. After all, they were the originators of the 4Cs in the 1940s, created by Robert M. Shipley who was the founder of GIA. The colours are graded from D-Z, clarity from Flawless-Included and cut from Excellent-Poor. Carat actually refers to the weight of a diamond instead of the size, but the two are very closely related. The size of a diamond is instead listed out as its dimensions measured in millimeters.

AGS - American Gem Society

AGS is arguably a superior lab to GIA in terms of its grading criteria, but for how well known they are for this, there are surprisingly few AGS graded diamonds around. Ironically, AGS was founded by Robert M. Shipley, GIA’s very own founder. AGS was initially not meant to be a competing lab, but instead to fill the gaps with regards to cut grading that GIA had. They follow the GIA grading criteria quite closely but with different denominations. Their colour, clarity & cut are graded 0-10, with each number corresponding to a grade in the GIA system, with 0 being the highest grade. 

GIA grading leaves the cut grade out of fancy shaped diamonds that are not round, whereas AGS has a cut grade even for these fancy shapes. Even for brilliant round diamonds, AGS’ 0-10 grading system has twice as many grades than GIA’s Excellent-Poor system. They developed a cut grading system based on the diamond’s proportions, making them the only scientifically verified system for determining the cut quality and light performance.

IGI - International Gemological Institute

“International Gemological Institute (IGI) is the World's largest Independent Laboratory for testing and Grading Gemstones and Fine Jewelry, renowned for its quality service and extensive experience.”

One of the most commonly used grading labs, however, IGI is notorious for its slightly inflated grading system. For the most part, they follow the GIA grading system closely, but have introduced an “Ideal” into the cut grade, which is one grade up from “Excellent”. There have been many case studies where the same diamond graded by GIA and IGI resulted in an inflated grade by IGI. This means that an E colour diamond graded by IGI could potentially end up being just an F colour diamond graded by GIA. While this is not always the case, there is that chance that an IGI certificate carries an inflated grade.

When clients are purchasing an IGI graded diamond and are particular about getting a colourless diamond, we usually recommend going for an E colour and above, just in case the IGI graded F colour is actually a G colour visually, which can be seen as slightly yellow by the trained naked eye.

IGI Certificates & Lab Grown Diamonds

With all that said and done, why are lab grown diamonds mostly IGI certified, and should you buy an IGI certified lab grown diamond? As we have already mentioned at the start of this article, unless you have an investment grade diamond, the specific grade of a diamond should not hinder you from getting the diamond you love. For example, VS clarity diamonds are often eye clean, meaning that despite the inclusions present, it should not be visible to the naked eye, nor affect the light character of the diamond, especially if the VS diamond is well selected with the inclusions not present in the table or face of the diamond. There is no need to spring for that flawless clarity just for the sake of it as it will cost you significantly more with little visual difference. Similarly, an F coloured diamond is hard to differentiate from a D coloured diamond to the majority of people, and after it is set into a piece of jewellery, the colour difference becomes even less obvious.

One of the main reasons that people purchase lab grown diamonds is because of the price, and the price often differs between a GIA & IGI graded lab grown diamond. There is usually an upcharge of a few hundred dollars to have a GIA graded diamond over an IGI graded one, and the upcharge can increase to the thousands as the diamond carat increases. This up-charge can account for approximately 10% of the diamond’s price which is a little excessive if you think about it since it doesn’t change how the diamond looks and performs to anyone who sees it. Being more affordable, IGI certified lab grown diamonds have become the norm and we do not see any issues with it. We do carry GIA certified lab grown diamonds too but try to look out for our clients’ best interests and advise them to save that price difference for a larger or higher quality diamond instead. Not to mention that the selection of GIA lab grown diamonds available is usually more limited than that of IGI.

While there has always been a spotlight on a diamond’s 4Cs, we must also be practical and understand the limitations of having a perfectly graded diamond. As long as the colour & clarity are within your acceptable range, without compromising on the quality of the diamond’s cut & proportions, that should allow you to own a high quality diamond that sparkles like no other. And despite GIA/AGS’ superior grading standards, having an IGI certificate for your lab grown diamond is more than enough. Speak to our consultants about what selecting a high quality diamond is all about.