Understanding Paraiba Tourmalines: Composition, Properties, and Market Factors

Paraiba tourmalines are a copper bearing variety of tourmalines, known for their neon blue to green colors and were first discovered in Brazil in the 80s. Since them these stones have been found in Africa as well.

Geological Origin and Classification

Paraiba tourmalines are part of the elbaite subgroup of the tourmaline family. What differentiates them is the presence of copper (Cu²⁺), sometimes combined with manganese (Mn).

Mines:

• Brazil (Paraíba & Rio Grande do Norte): Highly sought after with mine’s almost depleted nowadays the mines and under control of governmental entities, not allowing miners to explore the remaining reserves.

• Mozambique: Main source of current market supply.

• Nigeria: Minor production with intermediate characteristics.

Did you know: The term "Paraiba tourmaline" nowadays applies to all copper-bearing tourmalines, not just those from Brazil. Laboratory certification can confirm geographic origin when required.

Chemical and Physical Characteristics

Crystal System Trigonal

Hardness 7 – 7.5 (Mohs)

Specific Gravity 2.82 – 3.10 (typically higher in Cu-rich samples)

Refractive Index (RI) ~1.61 – 1.65

Birefringence ~0.014 – 0.020

Pleochroism Common; usually blue-green to greenish-blue

Color Origin

The characteristic colors of Paraiba tourmalines, blue, green, etc,... are caused by:

• Copper: Primary responsible for the vivid color.

• Manganese (Mn): May alter hue toward purple or pink tones.

Did you know: Traces of coper may also be found in Aquamarines from Pakistan, which gives them a much brighter and vivid blue color.

Spectroscopy and trace-element analysis are used to identify the copper content and assist in confirming authenticity and origin.

Treatments and Enhancements

Paraiba tourmalines are commonly subjected to heat treatment to reduce unwanted color components (e.g. Brownish undertone) and in some cases to improve clarity.

The heating is considered stable and permanent, and it can be detected by a gemmological laboratory with the use of proper equipment.

Evaluation Criteria

When assessing Paraiba tourmalines, buyers typically consider the following:

1. Color Saturation

• Stones with strong neon blue hues are generally preferred.

• Even coloration is rare; zoning is common.

• Different origins show different levels of color saturation and vividness, with Brazilian stones commanding a premium.

2. Clarity

• Clean stones are preferred and command a premium

• Moderate inclusions are acceptable due to the material’s nature.

3. Cut and Carat Weight

• Paraibas are often cut to maximize color rather than clarity.

• Larger stones with even color are uncommon.

Pair of Paraiba Tourmalines, from Nigeria

4. Origin and Certification

• Stones from Brazil carry historical value and command a higher price.

• Mozambique stones dominate the current supply.

• Gemological labs can confirm copper content and origin.

Market Context

The value of a Paraiba tourmaline depends on a combination of:

• Color quality

• Size and weight

• Transparency

• Origin

• Presence and type of treatment