A gorgeous example of October's birthstone — a cushion-shaped 5.44-carat Paraiba tourmaline set in a platinum ring — stole the show last week at Bonhams' auction in New York City when it fetched $533,900, which is nearly nine times the pre-sale high estimate of $60,000.
A companion pair of oval-shaped Paraiba tourmaline earclips with a total weight of 5.1 carats achieved $140,200, outpacing its pre-sale high estimate by more than $100,000.
Paraiba is the most prized tourmaline variety. The vivid teal, turquoise and neon blue stones caused a sensation when they were first discovered by prospector Heitor Dimas Barbosa in Brazil’s tropical, coastal state of Paraiba back in 1989.
They were so popular that the limited supply beneath “Paraiba Hill” — an area measuring 400 x 200 x 65 meters — became tapped out within five years.
In 2001, new Paraiba-like tourmalines were unearthed far across the Atlantic Ocean in Africa. Curiously, the African gems boasted the same color and chemistry as the South American-sourced originals.
Some gem experts believe that the uncanny connection can be attributed to continental drift, the theory that the Earth’s continents have moved over geologic time and that South America and Africa were once connected. Paraiba, on the far eastern tip of Brazil, would have been adjacent to the west coast of Nigeria.
Paraiba tourmalines are distinctly different from other varieties of tourmaline because they owe their intense blue color to trace impurities of copper. Others get their color from the presence of iron, manganese, chromium and vanadium. Gem dealers generally refer to copper-infused tourmaline as “Paraiba,” regardless of the origin.
Tourmaline comes in a wide variety of fiery, vibrant hues, such as red, green, yellow, orange, brown, pink and purple. October’s birthstone is even available in bi-color and tri-color versions. The name “tourmaline” is derived from the Singhalese words “tura mali,” which mean “stone with mixed colors.”
Tourmalines range from 7 to 7.5 on the Moh’s scale of hardness, which makes them durable enough to be used in any type of jewelry. Both tourmaline and opal are considered the official birthstones for the month of October.
Credit: Images courtesy of Bonhams.