Discovered in 1989, paraíba tourmalines are among the world’s most prized gemstones. These rare gems are renowned for showing intense blue colors.
The Discovery of Paraíba Tourmaline
In 1989, exceptionally brightly colored tourmalines were discovered in the state of Paraíba, Brazil. Researchers determined that these elbaite tourmalines received their intense coloration from copper. (The stones also contained manganese and often a bit of bismuth). These stones generated great excitement, and their prices soon exceeded $20K per carat. For paraíbas, color is more important than clarity. Eye-visible inclusions are easily tolerated and only make slight value differences.
Soon after the original discovery, similar tourmalines were found in Brazil’s Rio Grande Do Norte state, just north of Paraíba state.
Nigeria
In 2000, more tourmalines also colored by copper were discovered in Nigeria. Generally, the Nigerian gemstones didn’t have the same vivid saturation as the Brazilian material. However, the range of colors did overlap.
Mozambique
A few years later, still more copper-bearing tourmalines were discovered, this time in Mozambique. They also had colors similar to the Brazilian material.
Liddicoatite Paraíbas
In 2010, the Gübelin Gem Lab analyzed faceted cuprian-bearing liddicoatite tourmalines, possibly from Mozambique, with colors and concentrations of copper and manganese like elbaite paraíbas. In 2017, the Gemological Institute of America (GIA) analyzed similar specimens. These gemstones have appeared in gem markets. However, like most tourmalines, cut paraíbas belong predominantly to the elbaite species.
Identifying Paraíba Tourmalines
Paraíbas are elbaite tourmalines colored by copper (except, of course, liddicoatite specimens). They have a refractive index (RI) of 1.603 to 1.655 and specific gravity (SG) of 2.84 to 3.10. They have a high birefringence of 0.013 to 0.024, so you’ll almost always see doubling with your loupe. (See the main tourmaline gem listing for the properties of liddicoatites).
Paraíba colors are mostly green to blue. However, Mozambique has produced some pinks and purples. The main color criterion, however, is the saturation level, from 4, “Moderately Strong,” to 6, “Vivid.” Tones range from medium light to medium dark.
Chrome tourmalines are the only other tourmalines that approach a comparable saturation level (5). However, these gems have a higher RI, 1.772 to 1.778, and a much lower birefringence, 0.006. So, if you find an elbaite tourmaline with a saturation level of 5 or higher, you most likely have a paraíba.
On the other hand, if you have an elbaite with paraíba colors but a saturation of 4, you have to prove that it has copper content. A spectroscope reading will distinguish some of these gems. The key feature is a broad area of general absorption starting at 600 nm, present only in copper-bearing gems. However, a standard spectroscope will only distinguish stones with the highest copper content. Send the others to a major gem lab for testing.
Enhancements
Paraíbas may receive heat treatment. This will lighten stones with darker tones and change violet and purple colors into blues.
Although clarity doesn’t play a major role in paraíba value, these gems may still receive clarity treatments. For example, lasers can remove dark inclusions, and fillers may decrease the visibility of surface fractures. However, stones with evidence of clarity treatments will hold less value than untreated gems of similar qualities. As a result, paraíbas don’t receive these treatments very often.
Care
Avoid cleaning paraíba tourmalines with ultrasonic or steam devices. Vibrations and heat may cause liquid inclusions to expand, shattering the stone. Instead, use a soft brush, mild detergent, and warm water.
From Gem Society
