Science Reveals New Emerald Origin Test

February 1, 2000

Science Reveals New Emerald Origin Test

A new method of emerald analysis can determine the country and even the mine where an emerald was unearthed, says an article in the Jan. 28 issue of Science magazine. The article was written by a French and Colombian team led by Gaston Giuliani of the Center for Petrographical and Geochemical Research in Vandoeuvre-les-Nancy, France.

The method involves analyzing traces of water from which the emeralds crystallized. The researchers vaporized a small sample from the surface of emeralds and measured the ratio of two forms of oxygen isotopes found in the samples. Their research found every one of the known emerald mines in the world has water with different isotope ratios, enabling the researchers to identify a gem's origin. The minute pit left on the emerald's surface after the vaporization is invisible to the naked eye.

The research tested four emeralds from the treasure of the Nizam of Hyderabad in India, three of which were found to have come from mines in Colombia, though they previously had been attributed to other mines. It also tested other historic emeralds.

Though the method could be used to trace emerald origin in contemporary gems, its slight destructiveness may deter collectors from trying the method.

- by Peggy Jo Donahue