Peter Damian Arguello, a jeweler in the Denver suburb of Wheat Ridge, was found dead inside his store in November 2023.
GIA Creates Gem Guide for Artisanal Miners
The Gemological Institute of America has partnered with an NGO to train about 45 miners in the Tanga region of Tanzania using the guide.

Carlsbad, Calif.--The Gemological Institute of America has developed a gem guide for small-scale miners and partnered with non-governmental organization Pact on a pilot program training women miners in Tanzania using the guide.
A team of GIA gemology, market, education and design staff chose the content and form of “Selecting Gem Rough: A Guide for Artisanal Miners,” and consulted colored gemstone experts who have extensive experience buying gems in rural areas as well.
The guide was developed to offer basic gemological and market knowledge for artisanal miners in gem-producing regions, and was written in both English and Tanzanian Swahili. It includes almost every gem species mined in East Africa with illustrations of rough and polished gems and graphical instructions on how to prepare and examine rough under a number of lighting conditions.
“This project is at the very core of GIA’s mission,” President and CEO Susan Jacques said. “We are moving practical gemstone education as far up the supply chain as possible, to people who can benefit tremendously from greater understanding of the beautiful gems they bring to market.”
The area was chosen because of its diversity of gemstones and because the leadership of TAWOMA expressed interest in the guide, the GIA said.
The $120,000 cost of the pilot program came from the GIA’s endowment fund.
The institute provided the booklet and training at no cost, and the GIA said it will stay free of charge as it expands training to other small-scale rural miners in East Africa later this year.
The GIA said it and Pact will evaluate the program as it progresses to determine a time frame for the pilot.
“There is often a knowledge differential between artisanal miners and those further along the supply chain,” said Cristina Villegas, technical program manager for Pact’s Mines to Markets program. “This new GIA resource will help miners in rural areas better understand the quality and value of their products, which will help reduce that differential and improve their economic development opportunities.”
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