Paraíba Tourmaline: Properties, Origins, Treatments and Value

In the late 1980s a miner named Heitor Dimas Barbosa spent years digging into a hill at São José da Batalha in the Brazilian state of Paraíba on nothing more than a conviction that something was there. What came out, and reached the Tucson show in 1989, was tourmaline in a blue and green that no one had seen: saturated, luminous, apparently lit from inside. The cause was copper, which had never before been found colouring a tourmaline. The deposit was tiny, the stones were small, and the price rose faster than any coloured stone in living memory.

What it is

Paraíba is elbaite, the lithium tourmaline, with copper in the structure at concentrations of a fraction of a percent, usually accompanied by manganese. The mineralogy is otherwise that of any elbaite: trigonal, hardness 7 to 7.5, no cleavage, refractive index around 1.62 to 1.64 with a birefringence near 0.018, specific gravity a little over 3.0. What copper does is absorb across the red and yellow and transmit the blue and green with an intensity that iron, which colours ordinary blue and green tourmaline, never approaches. The result is a saturation the trade calls neon or electric, and the word is not marketing. Put a fine Paraíba beside an indicolite of the same hue and the indicolite looks asleep.

Where the colour comes from

Copper as Cu²⁺ is the blue and the green; the balance between them depends on how much manganese is present and in what state. Manganese also gives the violet and purplish tints most rough shows when it comes out of the ground, and gentle heating reduces that component, leaving the copper colour clean. The intensity of the neon depends on copper concentration and on the absence of iron, which greys everything it touches. The finest Brazilian stones carried a great deal of copper and very little else, which is why they glow at sizes where other stones barely register, and why a half-carat Paraíba can be a serious object.

Where it comes from

The original mine at São José da Batalha in Paraíba state is the reference and is nearly exhausted; neighbouring deposits in Rio Grande do Norte, at Mulungu and Parelhas, produced the same material in the same small sizes. In 2001 copper-bearing tourmaline appeared from Nigeria, and in 2005 from Mozambique, where the Mavuco deposit in Nampula province produced larger, cleaner crystals in colours that at their best match Brazil and at their ordinary level do not. The laboratories responded with a definition. Under the harmonised wording adopted in 2006, Paraíba tourmaline means copper-bearing elbaite in blue to green regardless of origin, and the report states the origin on its own line, supported by trace-element chemistry that separates the three countries with reasonable confidence. The trade has never entirely accepted this. Brazilian origin carries a premium for history and for scarcity, and a buyer should know whether they are paying for the colour, the copper or the country.

How it is judged

Saturation first, above every other axis, because saturation is what copper gives and what the price follows: a stone with the neon is Paraíba and a stone without it is a blue tourmaline with copper in its chemistry. Then hue, from the pure blue the market prefers through turquoise to green, with the greenish blues most prized and the greens priced lower. Then tone, where the trade wants medium and light stones that keep the glow rather than dark ones that swallow it. Then clarity, and Brazilian material is often included while Mozambican is often clean. Then size, where the price per carat curve is among the steepest in the trade: Brazilian stones above a carat of fine colour are rare and above three are historic, and Mozambique’s larger stones are priced as the objects they are.

Treatments, and what to demand on paper

Heat is routine and honest. Most rough is heated to remove the violet manganese component, at temperatures low enough that laboratories often cannot prove it either way and write that heating cannot be excluded. The market accepts this and prices accordingly. Fracture filling is a different matter: some Brazilian stones are heavily included and have been filled with resin, and a filled stone must be disclosed and is worth less. The report must do three things: confirm the species, measure the copper, and give an origin opinion. Without the copper measurement the word Paraíba is a hope. Without the origin line the Brazilian premium is a story. Copper-bearing glass and coated stones exist for the unwary, and the sequence of due diligence applies at Paraíba prices as it does at ruby prices.

The market

Paraíba went from unknown to one of the most expensive coloured stones per carat inside a decade, and it has not come back. The finest small Brazilian stones with Swiss or GIA paper trade per carat at levels comparable to fine unheated sapphire and, at the very top, beyond; fine Mozambican stones of size sit below that and are the only realistic route to a Paraíba above five carats. Below the top the market tiers steeply by saturation, and a great deal of pale, greyish copper-bearing material is sold on the strength of the word. The stone has no auction history to compare with ruby, because it has existed as a gem for thirty-five years, and its liquidity is thinner than corundum’s. It is a collector’s stone, priced like one.

Care

As for any tourmaline: hardness 7 to 7.5, no cleavage, sound for rings with care. Filled stones must be kept from heat and solvents. Included Brazilian stones should stay out of the ultrasonic. The colour is stable in light and heat at the temperatures a stone meets in a life.

Where I stand

Paraíba is a stone I hunt on mandate, and the discipline is the ruby discipline: colour in daylight against master stones, the copper measured, the origin argued by two houses where the Brazilian premium is doing serious work, and no money before the paper. I buy it for the neon or not at all, because a copper-bearing tourmaline without the glow is a tourmaline, and the name on the invoice does not light up a room.

Questions collectors ask

What makes Paraíba tourmaline so expensive?

A colour nothing else produces, from copper in the lattice: a saturated blue to green that appears lit from inside and holds at a distance. Add a supply that was tiny from the start in Brazil and is finite everywhere, and per-carat prices for the finest stones sit beside fine unheated sapphire and above almost every other coloured stone.

Is Mozambique Paraíba real Paraíba?

By the laboratories' definition, yes: the name describes copper-bearing blue to green elbaite regardless of where it was found, and the report states origin separately. By the trade's instinct, Brazilian stones carry a premium for history and rarity. Mozambique produces larger, cleaner stones; Brazil produced the most intense small ones.

Is Paraíba tourmaline heated?

Routinely. Most rough comes out of the ground violet or purplish from manganese, and gentle heat removes that component and leaves the copper blue. The treatment is stable, accepted, and often written on reports as heating that cannot be excluded. Fracture filling is a separate matter and must be disclosed.