Founded in 1998, The International Gem Society (IGS) was the first Internet-based school of gemology to serve a global audience. The goal was to reach people who could not otherwise afford a formal education in gemology. IGS’s founder, Donald Clark, created a robust testing process to ensure that those with IGS certification would stand out in the crowd. IGS continues to use the testing material created by Donald Clark to ensure continuity and rigor.

Certification Details

Course Materials
All the information you need is located on our website in our Reference Library. There are no other books required. The gemology course is divided into sections:

An Introduction to Gemology covers basic subjects of interest to the general public. These are non-technical articles designed to open the doors to a complex subject.

Advanced Gemology explains the technical terms used to define gems and introduces the more complex subjects.

Practical Gemology goes one step further, explaining how to use the tools of gemology and what to do with the information they supply. This is the essence of gem identification. This is the most difficult part to learn. It takes time and practice to learn how to use these instruments properly. Take one instrument at a time and master it before moving on to the next one. Intersperse this practice with your reading for the quickest learning. (See “Tools of the Gemologist” for a list of necessary instruments.)

Gem Grading details the factors used in grading diamonds and colored stones.

Advanced Gem Information gives details on specific gems.

Appraising Once you have learned how gems differ from one another, how to identify them and what properties determine their value, you can move on to appraising. The actual appraising is fairly simple after one has mastered gem identification and grading.

For beginners we have a structured syllabus, however you may study in any order that suits you.

The course is self-study. This means that all of the material is available in the Reference Library, and the burden is on the student to learn the material. There are no online tutorials or classes. The benefit of this approach is that each student can learn at his or her own pace, and on his or her own schedule. Students can take as long as they want to complete each exam in the certification process to ensure familiarity and understanding of the material.

Examination Process
In order to pass the certification process the student must:

(1) Pass three 100-question written exams with a score of 87% or better. Each individual exam must be completed within 90 minutes. The student may retake the tests an unlimited number of times until they pass each one.

(2) Thereafter, they must also pass a practical exam which requires identifying and grading 10 gemstones. We will send you the gemstones, which will be common to the trade and include natural, enhanced, synthetic, and assembled stones. Deductions will be made for errors, and the applicant must score 87% or better to pass.

When the written and practical tests have been completed with passing scores, the IGS-Certified Professional Gemologist certificate will be awarded.

All examinations are administered via online test-taking software accessed via your password-protected account on the IGS website.

Certification Cost: $350 *
The cost to become an IGS-certified Professional Gemologist is $400 with a $50 refund given if you choose to return the stones used for the practical test. (You may keep the stones instead, if you wish.)

Please note that certification costs are non-refundable.

* In order to gain access to the certification process, you must also be an IGS Gold Member ($59/year).

Why IGS?
Many people want to know how the IGS course compares with those offered by the GIA or similar organizations. Many are specifically asking how our gemologist certification compares to a GG degree. The GIA is an excellent organization. Their Graduate Gemologist degree is the most respected credential a person can hold in this industry. If you have the time and money, and are serious about a career in the gem industry, the GG course should be your first choice.

The IGS certification program was created for everyone else. The founder of IGS and author of the program, Donald Clark, has strong connections with the lapidary community. For years, he listened to amateurs giving inaccurate advice to others. For example, he heard things like: “If your blue stone has an RI of 1.625, then it is topaz, not aquamarine.” Those two properties, color and RI, also belong to tourmaline and a few rare minerals. Blue topaz and blue tourmaline have vastly different values. Not knowing the difference can be costly, in terms of both money and reputation.

Don believed that the problem stemmed not from the well-meaning lapidary sharing his incomplete knowledge, but that there wasn’t anywhere to learn gem identification, short of taking a $3,000 course. For them, he created IGS. It is dedicated to all the gem cutters, collectors, jewelers, and others wanting to know more about gems. The Professional Gemologist program was also created for those lacking the resources for a GG degree. A typical example would be a person making a midlife career change. This often involves working two jobs for a period, or the time consuming process of starting a new business.

What the certification tells a customer, or potential employer, is that the holder has proven their knowledge of gemology: that they are versed in its terminology, the properties of gems, how they are valued, and that they possess the skills and knowledge to distinguish one gem from another. But let us be clear: having a certification may open doors. Beyond that, it is the way an individual presents themselves and their work ethic that determines their success.


Hello Don,

Just wanted to thank you for the fantastic adventure I have had since becoming a member of IGS. The quality of your Gemology Course is tops. Nice to know that such folks as you exist. What a gift you give, passing this knowledge along to those of us who are seekers.

Thanks again,

Dr. John Parrott

Don Clark,

You are one heck-of -a-writer. This course is so well written, that I’m convinced that anyone, even me, can understand and master this material. After having read the first four introductory articles, I find myself actually wanting more time to study. It’s like a good who-done-it mystery. It just can’t be “put down.”



Dear Don,

I am writing this e-mail specially to extend my most grateful thanks to you (in fact on behalf of all the IGS members) for the variety of invaluable New Year Gifts you have accorded to the members for 2006. I feel, your dedication to “bringing quality information and educational services to everyone interested in gemstones” is truly one-of-its-kind. I, and most probably many other members too, owe our gemology knowledge to IGS. You are indeed our “Guru” in the true sense of the term. Your knack of simplifying the most complicated topics and your constant endeavor to update the existing information are really unique. Since, as you said you have more planned for this year than you will be able to complete, I wish God gifts you longer days which have 42 hours instead of the usual 24!

Thanking you once again and with Best Regards,

Nitin Pawaskar, Pune, India

Dear Don,

I have been on the distant sidelines of the jewelry business for a long time with a great love of colored stones and working with gold. I am committed to getting into the field full-time and even being self-employed and recognize the need for the credentials. I must tell you that IGS is a Godsend for me, as I do not have the resources or the six months required to get a GG from the GIA now. I really appreciate being part of the organization.

Thank you again


Charlie Bernheiser


I want to personally commend you on your article in the summer issue on the polariscope. I have told you I am self taught with only reference material. I am still trying to learn what I am reading from the article. Thank you for the lesson. This one article is worth five times the membership to IGS!

Thank You

A.C.Hughes, Panache’ Gems


I have never known or heard of an organization that offers so much for its members, and at such a low cost. You are so honest and helpful to the members. I hope you get the recognition that you deserve. What started as a hobby in 1998 and now is a small home business for my wife and I (we also have day jobs and two young children), has been made so much easier by the information you supply.

Thank You

Ernest and Peggy Roisch, Rainbow Rocks, LTD.

Hi Don,

Thanks for all the effort and work on IGS. It has helped me tremendously in many different aspects of my business, from faceting to pricing and even historical anecdotes that I can share with people at shows. I really appreciate what you are doing.

Thanks again,

John Lemieux Rose, 2 Roses Studios

Dear Mr. Clark

My sincere thanks for your time in providing the information! Everyone I asked had a clever “answer” which mostly included the much-touted “C” advisory put out by the diamond industry. Made it sound like a closely guarded secret known only to jewelers. I am only a humble collector (mostly garnets) seeking to provide practical information to my broker.

Thank you for encouraging an infant love of gemstones and for being so democratic in promoting the hobby. I have met with a lot of subterfuge. Your attitude is very refreshing and much appreciated.

Mrs. Donna Lambert

Dear Donald,

You know the best thing that I have learnt from your great courses is that it does not matter how much you think you about gems, you never stop learning, each day there is something more learn, it will never stop. Thank all for the help, education and support that you give IGS members.

Peter Checkley, One Very Proud Member

Dear Don,

Thank you for marking my exam as quickly as you did. I’ve spent a
tremendous amount of time and energy in preparing for this exam. I am very pleased with my results.

I found the couse material to be very complete and up to date. The exam
format forced me to review the course material over and over. I now feel I
have a pretty good handle on gem theory due to this format.


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