GIA GEMS AND GEMOLOGY ARTICLE:
this is an absolute must read!!!
NOMENCLATURE OF
“PARAÍBA” TOURMALINE
The Association of Gemmological Laboratories
(AGL) in Japan currently specifies that a blue-togreen tourmaline showing the characteristic “neon” color due to copper can only be called “Paraíba” as a trade name on an identification report when the stone is confirmed to be from Brazil. AGL allows the “Paraíba” name to be used for tourmalines from Rio Grande do Norte (Mulungu and Alto dos Quintos), since separating them from Mina da Batalha stones is difficult, and material imported into Japan is a mixture of tourmalines from both states. This policy is
consistent with that advocated by most gem dealers who are handling the Brazilian “Paraíba” tourmaline. However, as supported by the research reported in this article, Cu-bearing tourmalines from Brazil, Nigeria, and Mozambique are difficult to distinguish
from one another by standard gemological testing methods. Therefore, AGL and the Laboratory Manual Harmonization Committee (LMHC) decided to reconsider the nomenclature for “Paraíba” tourmaline. The LMHC consists of representatives from the AGTA-Gemological Testing Center (U.S.), CISGEM (Italy), GAAJ Laboratory (Japan), GIA Laboratory (USA), GIT-Gem Testing Laboratory (Thailand),
Gübelin Gem Lab (Switzerland), and SSEF Swiss
Gemmological Institute (Switzerland).
At the LMHC’s October 2005 meeting in Lucerne, and at the February 2006 Gemstone Industry & LaboratoryConference in Tucson, the LMHC group agreed to define “Paraíba” tourmaline as a blue (“neon” blue, or violet), bluish green to greenish blue, or green elbaite tourmaline containing Cu and Mn, similar to the material that was originally mined in Paraíba, Brazil; any “Paraíba” tourmaline, regardless of its
geographic origin, shall be described with the following wording on a gem identification report:
• Species: Elbaite
• Variety: Paraíba tourmaline
• Comment: The name “Paraíba tourmaline” is
derived from the locality where it was first
mined in Brazil.
• Origin: Origin determination is optional
This policy is consistent with current CIBJO
practice, which defines “Paraíba” tourmaline as having a “green to blue color caused by copper,” but no
definition is made according to locality. Thus, CIBJO
also considers “Paraíba” tourmaline to be a general
variety or trade name.
#paraiba #gia #agl #agta #cibjo #gemstones
