Hardness 7.5 specific gravity 3.0
Refractive index 1.62-65 birefringence 0.014-21
Wear: good durability
Paraiba tourmaline is the most valuable tourmaline. Because it contains copper, it has a unique neon color, which is very impressive.
The name "Paraiba" comes from the first copper bearing tourmaline found in the northeastern Brazilian state of Paraiba.
The history of the discovery of palaiba tourmaline
In 1982, mining began in the Mina Da Batalha tourmaline mine in palaiba, Brazil; in 1987, a small amount of tourmaline with bright blue tone was produced in this mine for the first time. In the same year, the gemologist Heitor Dimas Barbosa published a paper on the discovery of this gem.
In 1988, the Mina Da Batalha mine produced a total of about several kilograms of this bright blue tourmaline crystal raw stone, and cut hundreds of carats of high-quality bare stone. Shortly after the sale of the first cut stones, gem identification agencies such as GIA received samples. After analysis, it was confirmed that the rare blue of the new tourmaline came from "copper" and "magnesium".
From 1990 to 1991, the production of bright blue tourmaline at Mina Da Batalha mine peaked. At the Tucson gem show in 1990, the carat price of the new gemstone rose from hundreds of dollars to more than 2000 dollars in four days, and the supply of the new gemstone still exceeds the demand. People began to call it "Paraiba tourmaline".
From 1992 to 1996, the tourmaline mine of Mina Da Batalha fell into a dispute of ownership, and many forces competed for the mining right of the mine. From 1994 to 2001, the vast majority of palaiba tourmaline was obtained by re screening the old slag, and there were few bare stones with a cut thickness of more than 0.5ct.
In addition to the Mina Da Batalha mine, two mining areas have been found in palaiba state, one is mulungu mine, 60 km northeast of the Mina Da Batalha mine, where the output is less; the other is Alto DOS quintos mine, 45 km northeast of the Mina Da Batalha mine In this mining area, tourmaline of various colors is produced, and there are larger particles of copper bearing palaiba tourmaline.
In 2001, a copper bearing tourmaline similar to the Brazilian palaiba tourmaline was found in Nigeria, Africa, and in 2009, the same copper bearing tourmaline was found in Mozambique, Africa. The copper bearing tourmaline from these two places of origin can be heated to obtain a bright blue-green color very close to the palaiba tourmaline, so it is also called "palaiba tourmaline" in the transaction.
At present, "Paraiba tourmaline" has been widely used to refer to tourmaline with copper color and neon color.
Heating treatment of palaiba tourmaline
Almost all of the "Paraiba tourmalines" in the global gem trade are heated. When the copper bearing mauve tourmaline is heated between 480-620 ℃, it will become "neon blue & Turquoise Color".
Even in the Brazilian state of palaiba in the 1990s, more than 80% of palaiba tourmalines were improved by heating.
Factors affecting the value of palaiba tourmaline
Color is the most important factor, and high saturation and bright blue is the most popular. Because of the cracks in the "palaiba tourmaline", it is much more expensive to have a completely clean stone without cracks.
In terms of origin, the price of palaiba tourmaline from Brazil can reach several times that of Africa. Generally speaking, the color of palaiba tourmaline from Brazil is also higher than that of Africa.
Wearing and maintenance of palaiba tourmaline
Palaiba tourmaline is a kind of stone with many cracks. To avoid collision, it is not allowed to use ultrasonic cleaner for cleaning. Tourmaline is easy to absorb dust, and it should also be placed in a dust-proof jewelry box for safekeeping.