Stone Grading

Stone grading is the process of describing and quantifying the physical characteristics of a cut (or uncut) stone.

A stone identification report or gemological report is a descriptive document that lists the physical characteristics of a stone, including its measurements, weight, cut type, shape, color, species and variety, and also includes a picture of the stone. Reports issued by reputable grading laboratories also contain a unique ID number assigned by the issuing lab.

A certification, also known as a "cert", is just a more common nickname for a gemological report because the grading laboratory (or "lab") is certifying the characteristics and authenticity of the stone in question.

It should be noted that a gemological grading report is not the same as an appraisal. An appraisal is an expert estimate of the retail value of a stone or piece of jewelry. For all purchased jewelry pieces, Jewels and Gems will supply an appraisal for insurance purposes at no additional charge.

There are many stone grading laboratories worldwide. All are only as trusted and useful as their reputation. There are several reputable and widely accepted stone grading laboratories which we use and recommend:

  • American Gem Laboratory (AGL)
  • EGL USA Gemological Laboratory (EGL)
  • Gemological Institute of America (GIA)

EGL and GIA will grade either diamond or color stones, but in our opinion, both EGL and GIA have a better reputation for diamonds while AGL exclusively grades color stones.

The Gemological Institute of America (GIA), is by their own declaration "the world's foremost authority on diamonds, colored stones, and pearls", and you won't find many gemologists who would argue that point. The GIA is also a teaching institution, offering various courses and diploma programs for professional gemologists.

It's generally accepted that GIA wrote the rules on diamond grading. It was the GIA who created the 4C's of diamond grading (Cut, Clarity, Color and Carat weight). Watch GIA's videos on the "The 4C's of Diamond Grading".

Jewels and Gems

Jewels and Gems