AGA Position Paper on Diamond-Grading Procedures

May 11, 2008

On February 6, 2008, the Accredited Gemologists Association (AGA) held their annual conference in Tucson, AZ.  The event covered several issues regarding new treatments, new detection techniques and new technology.

A panel discussion titled "New Lighting Technology and Its Potential Impact on Color-Grading Fluorescent Diamonds" was held.  Mr. Stan Hogrebe, President – Dazor Lighting Solutions, was a member of the panel.  The panel also included Ronnie Geurts, Research and Development Mgr, GIA, Belgium; Peter Yantzer, Executive Director, AGS Laboratories; Jack Ogden, CEO, Gemological Association of Great Britain; and Tom Tashey, CEO, Professional Gem Sciences.

Mr. Hogrebe discussed the advances in lighting technology, including LED lighting systems.  He compared today’s lighting requirements for diamond-grading to the past lighting requirements. He noted that diamonds should be graded in a UV-free environment and referenced a statement by Robert Shipley, Founder GIA, which acknowledged "A light source as closely approximating daylight as possible…that lacks only the ultra-violet rays of daylight."  Mr Hogrebe went on to say, "…consistent and repeatable illumination in grading labs across the globe is achievable with today’s current lighting technology."  He stated that the scientific gemological community must develop standards for such things as; approved illumination technologies for grading diamonds, UV Wavelength in laboratory environments and the quantification of the UV content in the laboratory environment.

Because of the conference, the AGA has now published a position paper, which urges changes in color-grading procedures.  'The AGA contends that the grade now shown on most lab reports for fluorescent diamonds misrepresents the color[1]' and may mislead consumers.  The paper will be presented at the 2008 Las Vegas AGA Conference to be held on Friday, May 30, 2008 at the Platinum Hotel.

A complete copy of the published paper can be accessed here.

For more information about the AGA or the Conference, please click on the link below:

To request a copy of Mr. Hogrebe’s presentation, please contact

[1] AGA Position Paper, May 10, 2008

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