This is the talk of the gemology community this quarter.
GIA studies paraibas, lead glass-filled rubies
APRIL 24, 2006 - Carlsbad, Calif. – Two gems that have come up
on the gemological lab radar screen recently, “Paraiba”
tourmaline and lead glass-filled ruby, are the focus of a pair of
articles in the Spring 2006 edition of Gems & Gemology, the
publication of the Gemological Institute of America (GIA).
Leading the issue is “‘Paraiba’-type Copper-bearing Tourmaline
from Brazil, Nigeria, and Mozambique: Chemical Fingerprinting by
LA-ICP-MS,” by Ahmadjan Abduriyim of the Gemmological
Association of All Japan’s research laboratory and co-authors.
“Paraiba” tourmaline takes its name from the Brazilian state
where it was discovered in 1987. Lately, material has entered the
market of similar chemical composition but originating in Rio
Grande do Norte, Brazil, Nigeria and Mozambique. The article
compares the properties and compositions of these types of
tourmalines, concluding that their origin cannot be determined by
standard gemological testing, but require laser
ablation-inductively coupled-plasma mass spectrometry (LA-ICP-MS)
to establish a specific country of origin.
The second article, “Identification and Durability of Lead
Glass-Filled Rubies,” examines lead glass-filled rubies, an
increasingly common form of ruby treatment. Testing by Shane
McClure and a team of GIA Laboratory colleagues shows that the
lead-glass filler, effective at masking the appearance of
fractures, can be detected by careful examination with the
gemological microscope. While the filler was stable to most
jewelry repair procedures, it was damaged by exposure to a
standard jeweler’s pickling solution and some other common
liquids.
To order the Spring 2006 issue of Gems and Gemology, visit:
www.gia.edu