GIA vs. GSI & Everything Else You Need to Know about Diamond Certification

There’s no doubt that buying a diamond can be a daunting process. With so much information to sift through, it can be difficult to know what’s truthful and what’s simply opinion. This blog post will help to explain the different kinds of diamond certifications, like GIA, GSI and IGI, how Shane Co. grades their diamonds, and what to look for in a diamond to ensure you are getting the best value for your budget.

What is diamond certification?

A diamond certificate is a grade issued by an accredited independent gemological laboratory. It will inform the purchaser of all the known facts about the diamond, including its carat weight and measurements as well as grades for the other three Cs: cut, clarity and color.

While labs follow their own set of guidelines when it comes to grading, these guidelines are not universal among industry professionals. Ultimately, the grade is subjective, which means it’s the opinion of the particular grader of that diamond. Every independently graded diamond will come with a physical piece of paper with all of this information listed on it. The certificate will also include a graphic demonstrating the location of any inclusions/flaws within the diamond.

Loose diamonds.

Who grades the diamonds?

Shane Co. uses both an internal grading system as well as some of the world’s leading independent diamond grading laboratories. Often, we use multiple labs to ensure that our own grading standards fall in line with the rest of the world’s diamond experts. Because there is no universal set of criteria with which to grade a diamond, each laboratory (and, more specifically, each individual grader) could potentially provide a slightly different grade on the same stone. The most well-known diamond certification laboratories include:


The Gemological Institute of America created the 4Cs grading system and is known for having some of the strictest and most consistent grading standards of all the leading laboratories.


The International Gemological Institute tends to grade diamonds somewhat looser in color and clarity when compared to the GIA, but is still consistent in its grading standards.


The American Gem Society was the first lab to provide diamond cut grades, using its own cut grading scale, which varies from 0 to 9. Their grading standards are nearly comparable to GIA’s, and they have an excellent reputation for grading consistency.


Gemological Science International’s grading standards and consistency are similar to those of the IGI and GIA, making them another valuable resource for diamond certification.

Shane Co. grading

All Shane Co. diamonds are directly imported from the diamond capitals of the world after being hand-picked by Tom Shane and the rest of the Shane Co. buying team. We have worked with many of the same diamond cutters for generations, ensuring ethically sourced diamonds that are the prettiest in every grade. Because we buy our diamonds directly from the source in cash (instead of credit), we get first pick of all newly cut stones. In fact, our standards are so high that we end up picking only 1 out of every 10 diamonds we are shown.

After the diamonds make it to our jewelry experts, they are graded according to these same rigid and widespread quality standards, whether or not they are sent to an independent laboratory. Our internal experts are all GIA accredited and have had extensive training within GIA’s curriculum — a big part of this involves looking at hundreds of diamonds and aligning our eyes with industry leaders.

If a diamond you’ve been looking at has only been graded within our internal system and you still would like to have it inspected by an independent lab, we’re more than happy to send it out and have it graded for a fee. Our first priority is to make sure you feel totally comfortable with the quality of the diamond you’re buying.

Diamond subjectivity test

Ultimately, although certifications can provide a sense of security about the diamond you’re buying, the only way to truly know the quality of a diamond is to see it for yourself. Shane Co. offers an educational diamond subjectivity test in all of our stores. In this process, diamonds of the same grade are put next to each other and inspected both with the naked eye and with a loupe, so you can see for yourself the difference in quality between a Shane Co. diamond and its competitors, even within the same grade.

Check out the video below to see this process in detail.

Protecting your diamond

While most jewelers include some kind of warranty with the sale of an engagement ring, Shane Co. is one of the only stores that includes a completely free lifetime warranty that also covers your center stone. This is included in the price of your ring, which means that even if your diamond is somehow damaged, scratched or otherwise impaired, we will fix or replace it to its full value. We understand that this is a big and meaningful purchase, and we’re thrilled to be a part of your journey.

To learn more about diamond grading, visit our website, or explore our selection of loose diamonds online or in-store.

Notify of
Stay in the Loupe! Sign up for Shane Co. emails

Most Voted
Newest Oldest
Inline Feedbacks
View all comments

Charmaine Hi everyone

This post is so informative and interesting. I found it very helpful. Thanks and keep going.

You May Also Like