EDXRF Gem Testing: How X-Rays Reveal Chemical Elements

EDXRF stands for energy-dispersive X-ray fluorescence. It is a laboratory method for examining chemical elements in a gem without drilling a sampling hole. The long name describes a useful principle: elements emit characteristic X-rays when excited.

How the measurement works

An instrument exposes the sample to X-rays and measures the energies of the X-rays emitted in response. Peaks in the resulting spectrum help identify elements. With suitable calibration, the measurements can also provide information about their amounts.

SSEF’s 2011 article explains why this approach is useful for both loose and mounted gems. The article describes the introduction of a particular instrument at that time; it is not a statement about the laboratory’s entire current equipment.

What chemistry can help explain

Chemical data can support gem identification, colour research and some geographic-origin investigations. It becomes more informative when combined with knowledge of the material and reliable reference samples.

Understand the limits

Not every element is equally accessible to every analytical method, and the measurement conditions matter. A mounted stone also needs an appropriate setup. A chemical result should not be treated as a complete identification of every treatment or every origin. Ask which question EDXRF helped answer and what other observations supported the final conclusion. The best explanation connects the measured evidence to a clear statement about the stone.

Sources and further reading

SSEF Swiss Gemmological Institute, Facette, issue 18, January 2011, pp. 20, “Chemistry of Gems: new EDXRF at SSEF”. Read the original SSEF PDF.

This independent educational article explains historical SSEF research in original, simple English. It is not an SSEF publication. No source photographs or illustrations are reproduced.