The Gemological Institute of America (GIA) has completed its 100th field gemmology expedition with the landmark trip taking GIA researchers to Kenya and Tanzania, where they collected tsavorite, spinel, and sapphire rough.
The field gemmology programme contributes to GIA’s growing database on the chemical, geological, and gemmological properties of coloured stones.
Expanding GIA’s Coloured Stone Database
During the expedition, GIA field gemmologists collected over 15 kilograms of gem rough, including more than 10,000 carats of individual sapphires from Garba Tula, Kenya. Each sample’s origin was verified and recorded.
“Our extensive field gemmology programme is the foundation of our coloured stone research and identification and country-of-origin services,” said Tom Moses, GIA’s chief laboratory and research officer. “With over 29,000 verified samples—some comprising several hundred individual stones—and more than one million carats from 20 countries, we have the most complete and detailed database of the chemical, geological, and gemmological properties of coloured stones from mining locations around the world.”
Observing Mining Practices
As part of their research, the GIA team documented tsavorite and tanzanite mining operations, including conditions underground. They examined the challenges associated with artisanal mining and environmental conservation and observed mining activities in the Mahenge region of Tanzania, where demand for spinel has led to increased mining.
Over the years, GIA’s field gemmologists have visited all major ruby, sapphire, emerald, and spinel-producing regions across Asia and Africa, gathering data on gem deposits. The collected samples are used for research and shared with academic institutions. The information also supports GIA’s coloured stone identification and origin report services.
Contributions to Industry Research and Education
Wim Vertriest, manager of field gemmology at the GIA laboratory in Bangkok, described some of the findings from past expeditions. “GIA’s gemmologists documented the development of the Mozambican ruby mines from their discovery in 2009 to becoming the world’s leading source of ruby. We were also the first team of foreign gemmologists to visit the Ethiopian emerald mines after their discovery in 2016.”
Findings from these expeditions also inform GIA’s gemmology education programmes. Research results are published in Gems & Gemology, GIA’s professional journal.
