the Ethiopian Emerald is certified by The GIA

https://www.gia.edu/gems-gemology/spring-2017-gemnews-new-discovery-emeralds-ethiopia

GEM NEWS INTERNATIONAL

A New Discovery of Emeralds from Ethiopia

Nathan Renfro, Michael Nemeth, and Ziyin Sun

January 30, 2017

Figure 1. This suite of untreated emeralds is from a new find in Ethiopia. The largest faceted stone weighs 10.64 ct. The largest rough crystal weighs 315.61 ct. Photo by Robison McMurtry, courtesy of Michael Nemeth Inc.

In recent years Ethiopia has gained considerable attention in the gem trade for large amounts of high-quality opal from an area near Wegel Tena (B. Rondeau et al., 2010, “Play-of-color opal from Wegel Tena, Wollo Province, Ethiopia,” Summer 2010 G&G, pp. 90–105). A new deposit of high-quality emeralds (see figure 1) has been found in the rural villages of Kenticha and Dermi, in the Seba Boru district (figure 2). In November 2016, author MN and business partner Daniel Kifle visited the local trading town of Shakiso, where Ethiopian gem merchants gather to legally buy and sell emeralds that are mined several kilometers away. The mining area is divided into a few “associations.” Each consists of a manager and several members who control the actual mining and distribution of the emerald rough. After the rough has been sorted, it makes its way first through Shakiso before being sold to dealers in the capital city of Addis Ababa, about a 12-hour drive from the mining area.

Figure 2. The new deposit of Ethiopian emerald is located near the town of Shakiso.

According to Mr. Tewoldebran Abay, the mineral marketing director of the Ministry of Mines, Petroleum and Natural Gas, more than 100 kilograms of emerald rough have been produced to date. Mining still is done the traditional way using hand tools, without heavy machinery. Even though most of the material is commercial grade, lighter in saturation and moderately to heavily included, fine gem-grade crystals of exceptional size, color, and clarity are obtainable and can produce stones that do not require clarity enhancement (figures 1 and 3).

Figure 3. Author Michael Nemeth sorts through parcels of gem-quality rough emeralds from the open market in Shakiso. Rough crystals can weigh more than 100 ct, with reports of some weighing almost 500 ct. Photo by Michael Nemeth.

Due to heightened tensions and fear of price instability, most of the mine area was temporarily closed by a joint effort of the mining associations and the local government from early November through December 2016. It has been reopened, but now all dealers, including Ethiopian dealers, need written permission to enter the Shakiso area for buying. The law is vigorously enforced, and penalties are severe.

These emeralds are very similar in appearance to other schist-hosted emeralds—in particular, those from Brazil and Zambia. Among the faceted and rough samples examined, blocky multiphase inclusions and irregular biotite crystals were the most common microscopic features observed (figure 4). Otherwise, the gemological properties were very consistent with emeralds, including an average specific gravity of 2.73 and a refractive index of 1.581–1.589. These emeralds were generally inert to long- and short-wave UV exposure due to their moderately high iron content, which is typical of schist-hosted emeralds. UV-Vis-NIR spectroscopy results were consistent with emeralds colored by chromium and vanadium. The FTIR spectrum was consistent with beryl, as expected, but did not reveal any other diagnostic features.

Microscopic features observed in Ethiopian emerald

Figure 4. Microscopic observation of the Ethiopian emeralds revealed biotite crystals (left) and blocky multiphase inclusions (right). Field of view 2.04 mm (left) and 1.79 mm (right). Photomicrographs by Nathan Renfro.

Quantitative trace element chemical analysis was performed with a Thermo Scientific iCap Q inductively coupled plasma–quadrupole mass spectrometer combined with a New Wave Research UP-213 laser ablation unit. The analyses were compared to data from other known sources using GIA reference samples, including Zambian and Brazilian schist-hosted emeralds. Based on the results, it was possible to separate the new find of Ethiopian emeralds from other sources by comparing trace alkali metals and some transition metals (figure 5).

LA-ICP-MS quantitative analysis of trace element composition

Figure 5. LA-ICP-MS quantitative trace element composition analysis of alkali and some transition metals (measured in ppmw) proved useful in separating this new deposit of Ethiopian emeralds from Brazilian and Zambian schist-hosted deposits.

This exciting discovery in Ethiopia will provide a new source of large, high-quality emeralds for the gem and jewelry trade. Only time will tell how significant this deposit will be.

ABOUT THE AUTHORS

Nathan Renfro is analytical manager of the gem identification department and microscopist of the inclusion research department, at GIA in Carlsbad, California. Michael Nemeth is owner of Michael Nemeth Inc. in San Diego, California. Ziyin Sun is a staff gemologist at GIA in Carlsbad.

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