Grading

In the last two decades there has been a proliferation of certification, not only for diamonds but for gemstones as well. There are five 5 major laboratories which grade and provide reports on gemstones.

  • Gemological Institute of America (GIA)
  • American Gemological Society (AGS) is not as widely recognized nor as old as the GIA but garners a high reputation.
  • American Gem Trade Laboratory which is part of the American Gem Trade Association (AGTA) the largest trade organization of jewelers and dealers of colored stones.
  • American Gemological Laboratories (AGL) which was recently taken over by “Collector’s Universe” a NASDAQ listed company which specializes in certification of many collectables such as coins and stamps.
  • European Gemological Laboratory (EGL).

Although certification can provide certainty and clarity, each laboratory has its own methodology to evaluate gemstones; grading experience is different and depending on the cert required each lab approaches these issues differently. Consequently a stone can be called “pink” by one lab while another lab calls it “Padparadscha”. One lab can conclude a stone is untreated, while another lab concludes that it is heat treated. Countries of origin has sometimes been difficult to find agreement on due to the constant discovery of new locations. Gem labs need time to study them. Moreover determining a “country of origin” does not have the exact scientific methods at its disposal as other aspects of a gem (such as cut, clarity etc.)

Gem dealers are fully aware of the differences between gem laboratories and will make use of the discrepancies to obtain the best possible cert. One such example is to make use of the differences in “Country of Origin”: a sapphire from Kashmir (celebrated for its cornflower blue color) commands four times the price of the same stone from Ceylon and twice the price if the stone were from Burma.

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