Storefront on Jeweler's Row in Philadelphia

Tuesday, October 26, 2010

GIA Laboratory Tour

Last week while visiting New York, I got an exclusive tour of the Gemological Institute of America's (GIA) diamond grading lab.  It is a three story complex with over 200 professional graders evaluating the cut, color and clarity of diamonds, colored gemstones, and pearls.  Everyday, thousands of precious gems are sent to the GIA Lab to be evaluated by their staff of experienced graders.  The lab itself is extremely high tech.  Some of their more precise equipment is worth hundreds of thousands of dollars.  Not to be confused with the millions of dollars in diamonds circulating their halls on a daily basis.  Everything in the building is a neutral gray color in order to maintain a standardized light environment for grading.  Even the smallest amont of colored light can pollute the lab and produce inaccurate results that could affect the accuracy of grading reports.

The most interesting area of the tour was easily the colored diamond grading area.  Here, they have master stone sets of the rarest colors of diamonds including yellows, pinks and blues.  Just one of these fancy colored stones is worth a fortune, let alone a standardized set of them used for grading purposes.  Another interesting area was where they grade diamonds based on their proportions.  Instead of spending countless hours grading each individual stone for its various angles, depth and height percentages, they have a sophisticated machine that can calculate all this information in seconds.  This machine shines a special light through the stone, and a computer analyzes its shadow and measures its proportions.  They also have special lasers that are capable of inscribing serial numbers on the girdles of diamonds.  This machine was even more impressive considering that each one of these numbers are a fraction of a millimeter in size.  However, despite the extreme sophistication of the lab's technology, the vast majority of grading is done by individual graders under a 10x power microscope.  10x magnification is the GIA standard for grading.  If a characteristic can't be seen under 10 power, then the GIA does not plot it on the grading report.

The distribution system at the GIA lab was also very interesting.  In the past, graders would simply pass off stones to the person next to them for further evaluation, which caused some issues with anonymity and subjectivity in grading reports.  Now, diamonds are sent to a distribution office within the lab each time the stone changes hands for further evaluation.  This ensures that once a diamond enters the lab, it is essentially anonymous which allows for a less biased report.  It is these types of ethical standards that set the GIA apart as the premier authority on gemstones in the world.  The lab takes exhaustive procedures to ensure consistency within their laboratory grading procedures.  

Here at Sydney Rosen Company, we deal extensively with GIA certified diamonds and gemstones.  A report from the GIA is the simplest and most accurate way to ensure that you are getting a quality diamond for you money.  A GIA report, as well as a detailed appraisal accompanies every purchase made at our store.  

For more information on diamonds and other gemstones, visit  

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