Examples of the new Paraíba tourmaline production from Ethiopia, including a 7.64-carat faceted stone and an 8.70-carat rough stone. (Photo courtesy of the Ferreira Group/Photo credit: Annie Haynes/GIA)
Carlsbad, Calif.—Two gemological labs have confirmed a newly discovered source of Paraíba tourmaline in Ethiopia.
Following independently conducted investigations, the Gemological Institute of America and Gübelin Gem Lab confirmed that the East African country is producing copper-bearing tourmaline that meets the widely accepted definition of Paraíba tourmaline.
The labs separately acquired their reference samples, which researchers analyzed using each laboratory’s respective research protocols.
Both labs’ findings are consistent in confirming the new source, they said.
Reports of the potential new source, along with preliminary observations of material attributed to the new deposit, began circulating in the trade earlier this year.
The labs said they recognized the significance of a potential new source but waited until the provenance of their reference samples could be established with confidence and “sufficiently comprehensive” analytical datasets had been collected before making their conclusions.
The Gübelin Gem Lab first encountered the new material in early May.
It displayed “an unusual chemical composition” that did not match existing reference data from Brazil, Mozambique, or Nigeria, the lab said.
The lab said these observations preceded widespread reports of the new Ethiopian source and prompted further investigation.
Over the following weeks, the Gübelin Gem Lab assembled approximately 300 rough and faceted stones from independent sources.
It included material obtained through a private dealer as well as samples acquired during a visit to Ethiopia by one of the lab’s senior gemologists, who worked with local dealers with direct access to material from the mining area.
The collection served as provenance-supported reference material for detailed gemological, spectroscopic, and chemical analysis, the lab said.
“What is most striking about the Ethiopian material is that despite considerable, complex chemical variation between individual samples, they share a remarkably distinct and coherent compositional signature,” said Dr. Peter Tollan, head of research and development at the Gübelin Gem Lab.
“This means that the Ethiopian samples are readily distinguishable from all other origins of Paraíba tourmaline, without the need for research-grade analytical methods such as LA-ICP-MS [laser ablation–inductively coupled plasma–mass spectrometry].”
These rough stones from the newly discovered Paraíba tourmaline deposit in Ethiopia show the range of color the material is displaying. They weigh between 4.20 and 10.95 carats. (Photo courtesy of the Ferreira Group/ Photo credit: Annie Haynes/GIA)
At GIA, gemologists began examining parcels of material presented as originating from Ethiopia in early June.
In July, Ferreira Gems, a family-owned company that deals in Paraíba tourmaline, sent a parcel of more than 100 rough and faceted samples to GIA’s research department in Carlsbad, California.
The donation allowed for a detailed scientific investigation of the material and its characteristics, the lab said.
“We can confidently identify Ethiopia as an origin on GIA Tourmaline Identification and Origin Reports,” said Dr. Aaron Palke, GIA’s senior manager of research and a noted expert on colored gemstones.
“We extensively documented the material’s characteristics, adding this important information to GIA’s expansive database of colored stone origin information.”
Material examined during both investigations confirmed that the tourmaline from the Ethiopian deposit is colored predominantly by copper, falling within the Laboratory Manual Harmonisation Committee’s definition of Paraíba tourmaline.
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The material encompasses blue to bluish-green colors as well as violet, purple, and colorless in some rough specimens. Many stones display pronounced color zoning and related compositional variation.
Analyses by both laboratories also revealed elevated (>60 ppm) concentrations of vanadium, combined with elevated levels of lead (170-6000 ppm) and gallium (280-900 ppm).
These are “sufficiently strong identifying chemical properties,” the labs said, and all are easily measured with a good quality ED-XRF (energy-dispersive X-ray fluorescence) system.
A new source of Paraíba tourmaline is an important development for the colored gemstone industry, the labs noted.
Robust reference datasets will be essential for identification and for reliable determination of geographic origin as the Ethiopian material enters the international market, they added.
Both laboratories said they will continue to expand their reference collections and evaluate the range of characteristics displayed by Ethiopian material as more samples become available.
GIA and Gübelin Gem Lab will publish separate articles on their research in an upcoming issue of GIA’s quarterly journal, Gems & Gemology, presenting the full results of their investigations, including detailed gemological, spectroscopic and chemical data and discussion of geographic origin determination.
The two laboratories said they welcome the opportunity to communicate their conclusions together.
“Independent research, robust provenance, and the open exchange of scientific observations between gemological institutions are important for maintaining confidence in geographic origin determination, particularly when significant new gemstone deposits enter the market,” the labs said.
