Fluorescence Nomenclature
January, 2003

The AGS Laboratories Board of Managers recently voted to make a change to the fluorescence nomenclature on the AGS Laboratories reports. Currently the AGS Laboratories' fluorescence nomenclature is 'inert', 'faint', 'medium', 'strong', and 'very strong'. 'Medium', 'strong' and 'very strong' are followed by the color of the fluorescence. This is usually blue in diamond but may be other colors such as yellow, orange, red, and white.

Effective January 1, 2003, the 'inert' and 'faint' fluorescence descriptors will be replaced by a single descriptor - 'negligible'. The definition of the word 'negligible' is "Not significant or important enough to be worth considering." The Gemological Committee of the AGS Laboratories unanimously recommended the change in nomenclature to the Board. 'Inert' is an absolute term and, depending on the strength of the long ultraviolet fluorescence source, some diamonds described as being 'inert' might exhibit a minute amount of fluorescence.

Since the beauty of a diamond that is truly inert or exhibits 'faint' fluorescence is not adversely affected in any way, the descriptor 'negligible' is more accurate and more appropriate.

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