Why you need an AGS Lab Report on your diamond! – Interview with Peter Yantzer Executive Director American Gem Society Laboratories S4EP5 Diamond Answer Man

by Admin


Wow what a great show we have ahead!

Its not to often that I have guests on the show – I’m very very excited to welcome you to the Diamond Answer Man Show Season 4 Episode 5.

If you are in the market for a diamond – sit back and listen. We have Peter Yantzer the Executive Director of the American Gem Society Laboratories on the show today. This show is about 1 hour long.

Wow made what a putz I am! Dialed the number wrong the first time!!

Here are the notes from our questions – However listening to the show you will find far more in depth details of the WHY you need an AGS report.

Enjoy the show!

J. Christopher

  1. What is the AGSL grading process.

Stones go to weights and measures where they are also checked using the DiamondSure device which tests for natural diamond or refers for further testing.  Depending on the results of the DiamondSure it may also be checked with the D-Screen device.  Depending on the results of the combination of DiamondSure and D-Screen results it almost always ends up in research for further testing for Synthetic origin, HPHT treatment or simulants.

Once that is accomplished it goes through the grading process for Cut, Color and Clarity.


What are the checks and balances?

Every stone is graded by at least two graders.  Disagreements are looked at by a third person (supervisory level).  Clients can request a recheck of the grading and it is rechecked by supervisory personnel.



We are a top tier laboratory.  In order to earn that reputation we have had to prove that we grade consistently and accurately for the past 20 years.  That’s why we have a robust set of Quality Assurance procedures.



  1. How has the AGSL performance cut grade system positively changed the industry?

Previous to the AGS 3D Cut Grading Process diamonds were cut graded by looking at the table diameter%, the average of the crown main facets and the average of the pavilion main facets.  This method worked OK for its time.

The AGS Light Performance System took the grading of diamond cut to a 3 dimensional level.  We have at least a dozen patents for our metrics and methodologies.  Our system fully measures the effect that all of the facets on a diamond have on its light performance.  This method is still leading edge technology 10 years after its introduction in 2005.



Being able to assess diamonds in 3 dimensional space rather than two dimensional averages allows us to create light performance metrics and grading systems for almost any shape and facet arrangement.  Not all shapes perform the same.  Nor do different facet arrangements perform the same.  We can analyze the light performance and if there is enough business potential we can develop a grading system for it.  That is an interesting story in and of itself.

Because all the facets matter with respect to light performance our analysis has led the industry to cut much more consistently and accurately than in the past.

We also help the industry optimize existing cuts as well as new cuts.  This helps the industry bring new cuts to market and breeds creativity.  All pluses for our industry, wouldn’t you say?


  1. How do you approach the 4 C’s in preference of priority.

The American Gem Society has always ranked the 4 C’s in this order:  Cut, Color, Clarity and Carat Weight.  I think you can argue the order of color and clarity but I don’t think you can argue that Cut is by far the most important.  Carat weight is really the least important but because of human nature being what it is Carat Weight is usually ranked the highest by consumers.  For example, the psychology of a 0.98 carat diamond versus a 1.00 carat diamond still holds sway over many consumers.


  1. What “C” would you see added to the report of the future?

Certificate.  I have been lobbying for a “True” Certificate for years.  A “True” Certificate would guarantee the quality of a diamond.  Most grading laboratories don’t guarantee anything.  Currently a top tier laboratory issues an expert, unbiased third party opinion as to the quality of the diamond.  It also provides increased confidence by testing to make sure the diamond is a natural diamond and hasn’t been treated in any way.


  1. How should the trade respond to fraudulent reports to boost consumer confidence.

Don’t trade in diamonds with reports from fraudulent or loosey goosey or less respectable diamond grading laboratories – you pick which adjective you prefer.


  1. Over your career what stands out as most memorable.

From a professional view there are two:

Being hired by the American Gem Society to build and direct their diamond grading laboratory.  That was a lot of hard work but immensely satisfying.  And it’s most important to note that one person didn’t do it.  I worked with a great team of people over the years that all did their part and more.

Being chosen to lead the Research Team that developed the AGS Light Performance cut grading system.  That also was a lot of hard work but immensely satisfying.  And it’s most important to note that one person didn’t do it.  I worked with a great team of people over the years that all did their part and more.


  1. What is the weirdest ? that has come through the AGSL

We specialize in grading colorless to light yellow or brown diamonds only.  So we don’t get to see colored stones or fancy color diamonds.  With that in mind I think the various treated diamonds that have come through the lab in the last 20 years are the weirdest.  The detection of treatments is always reactive in nature.  Someone develops a treatment.  If ethical they tell people how to detect it.  If unethical, they try to put something over on people to make more money.  It’s impossible to be proactive because we don’t know who, what, when or where the next treated stone will appear.

The recent revelation that there is an unknown type of coating being applied to diamonds to improve their color comes to mind.


  1. If you could choose five people to have dinner with that have influenced the diamond world – who would they be and why?

Richard T. Liddicoat Jr, GIA West Coast.  He was a father figure to me when I was a fledgling gemologist.  He also was unflappable and had an extraordinary memory.  He could remember a person’s name that he may have met once five years previously.  What a great people person he was.

Robert Crowningshield, GIA NY. A nice man and a great gemologist.  His spectroscopy work is legendary.

Bert Krashes, GIA NY.  Not only a great gemologist but he was a great communicator and teacher.

Chuck Fryer, GIA West Coast.  An exceptional gemologist who taught me a lot of really good gemology.  He had an acerbic wit.  And, unlike me, had a no nonsense work ethic.

Gabi Tolkowsky.  Still the world’s most famous diamond cutter in my opinion.  He cut some of the world’s biggest diamonds and created many new designs.  His likability and his passion for diamonds have no equal.


  1. Final Question
    What advice would you give to today’s engagement ring buyer.

Buy a diamond with a report ( and hopefully someday a certificate ) from a top tier grading laboratory like the American Gem Society Laboratory. That relieves the buyer of having to worry about the authenticity and quality.  Then the buyer can concentrate on the value.  Do your homework to establish value in your mind and then buy with confidence.

Buy the best performing diamond you can afford.  It will always sparkle the most and never cease to cause people to comment on how beautiful your beloved’s or your diamond looks.  To do that you may need to sacrifice in one or more of the other three C’s but it is well worth it.

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