CS Book 3- AS 15- Emeralds PDF
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Gemological Institute of America
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Summary
This document details the key concepts related to emeralds, including their properties, trade, and mining. The document covers the geological factors affecting emerald value, the mining processes, and the global emerald industry.
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Emerald KEY CONCEPTS The trade considers emerald to have the finest green among colored stones. In Colombia, modern mechanized mining of emerald by private companies began in 1977. Slight differences in hue, tone, and saturation can make a great difference in emerald value when other factors are equal...
Emerald KEY CONCEPTS The trade considers emerald to have the finest green among colored stones. In Colombia, modern mechanized mining of emerald by private companies began in 1977. Slight differences in hue, tone, and saturation can make a great difference in emerald value when other factors are equal. In Colombia, blasting extends the mine tunnels while hand picks are used to carefully remove the emeralds. The most desirable emerald colors are bluish green to green, with strong to vivid saturation and medium to medium-dark tone. Government geological surveys suggest that only 20 percent of Colombia’s emerald reserves have been mined. Chromium, vanadium, and iron are the trace elements that influence emerald’s color. Don’t use a source name unless you know the emerald came from that source. Most facet-grade emerald mined in Brazil is from the Itabira, Nova Era, and Capoeirana areas. Zambia’s Kagem mine produces an estimated 20 percent of the world’s emerald supply. The trade generally accepts the presence of eye-visible inclusions in emeralds. Jaipur, India, is the global leader in the cutting of Zambian emeralds. Inclusions that reduce transparency or that are highly visible can have a strong negative effect on emerald value. Colombia and Brazil cut most of their better-quality emerald rough and send the lower-quality material to Jaipur, India. Emerald’s fractures are often filled with oil or resin or a mixture of both. India is the number one supplier of emerald to the US in terms of total carats, while Colombia is number one in total value. Gentle scrubbing with warm, soapy water is the safest way to clean emeralds. Switzerland is the number one exporter of emerald to the US in terms of per-carat price. Emerald is mined primarily from hard-rock sources rather than secondary ones. Today, hydrothermal is the primary synthetic emerald growth method. 253
