U.S. Geological Survey (USGS) historically has not attempted to report comprehensive world production of gemstones on a country basis. This was because estimation of gemstone production is inherently difficult due to the fragmentary nature of the industry, the lack of governmental oversight or reporting in many countries where colored gemstones are mined, and the wide variation in quality between individual gemstones. Unlike diamonds, which, with the exception of the alluvial stones of West Africa, are mainly produced by large international mining companies and evaluated, cut, and marketed through a highly developed pricing structure and complex commercial arrangements, colored gemstones are mainly mined by individuals or small companies and have less developed evaluation and marketing arrangements. The trading centers for colored gems are smaller and less well known than the diamond centers. Colored gemstones, like alluvial diamonds, have the potential to be used to fund civil conflicts and other illegal activities, and because trade in colored gemstones is less organized than that of diamonds, they offer less opportunity for effective regulation of their trade. And, like diamond, until the recent advent of the Kimberley Process no generally accepted estimates of colored gemstone production globally or by producing country have existed. The present paper is a first attempt to develop production statistics for the three precious gems -emeralds, rubies, and sapphires - and tanzanite tanzanite, a semi-precious gem. The data consist of the weight of production of each of the gemstones from 1995 through 2005. Preliminary data on the weights of gemstone production were presented as a poster session at the Gemological Institute of America's Gemological Research Conference in San Diego, CA, in 2006, and as a published abstract (Yager, 2006) in an attempt to gather response to the estimates. The USGS continues to welcome information and suggestions that would improve the data presented here.

Information used to make the production estimates presented in this paper include annual USGS Mineral Questionnaires completed by producing countries, data on exports from producing countries, reports from the literature, and company reports.

Comparisons of the weight and the value of production of a type of gemstone between countries may differ considerably. Whereas east African countries dominate the weight production of rubies, Burma (Myanmar) is widely thought to have the highest value of ruby production. Data on the value of gemstone production are even more difficult to estimate than is the weight of production. Value of production is dependent upon both the quality and the sizes of the stones produced. Such data are not readily available and are difficult to estimate; therefore this report does not present tables of values of production. Instead, the report briefly discusses the forms in which gemstones are sold, the systems used to value the gemstones, and selected data that illustrate the variability of value of gemstones of a particular type.