Emerald, geographic origin
Giuliani, Gaston Centre de Recherches Pétrographiques et Géochimiques, Vandoeuvrelès-Nancy, France.
- Oxygen isotopes
- Trade routes
- Tracing the sources of gemstones
- Links to Primary Literature
- Additional Readings
Emerald with lapis-lazuli is the oldest known gemstone, having been mined since ancient times in Egypt and probably in Bactria and Scythia. Emerald is rarer than diamond and may have a value thousands of times that of gold. Colombia produces 60% of the world's emeralds (total world production in 1986 was estimated to be 15 million carats), followed by Zambia (15%), Brazil (10%), Russia (5%), Madagascar (3%), Zimbabwe (2%), and Pakistan and Afghanistan (together 5%). Colombian emeralds are prized for their exceptional color, clarity, and carats, as are those from Afghanistan, and to a lesser extent Zambia and Russia. The mineralogical and gemological properties that are normally used to determine the origin of emeralds are their optical features (refractive indices and birefringence), density, adsorption spectra (ultraviolet and near-infrared), internal characteristics (growth phenomena and solid and fluid inclusions), and chemical composition. The diagnostic value of these properties is often restricted because there may be an overlap for emeralds originating from different deposits. However, a combination of mineralogical and gemological properties can be used, in many cases, to accurately identify emeralds from specific localities. Nevertheless, gemological features are often insufficient to certify the origin of gems, especially emeralds of excellent quality that are poor in inclusions. Thus, doubt or ambiguity always exists when determining the geographical origin of cut or carved emeralds removed from the environment in which they formed.
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