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Chemistry · Gemology & Science

The Role of Copper in Paraíba Tourmaline

Copper is the defining chromophore of Paraíba tourmaline. Understanding how it produces colour explains both the stone’s appeal and why it must be tested.

By
Paraiba Ethiopia Editorial Team
Reviewed by
Review pending
Updated

How does copper create colour?

Cu²⁺ ions in the crystal absorb red and near-infrared light. The remaining transmitted light is perceived as blue to green.

  1. Step 1

    Substitution

    Cu²⁺ substitutes in the tourmaline structure, mainly at the Y site.

  2. Step 2

    Absorption

    Electronic transitions absorb red and near-infrared light.

  3. Step 3

    Transmission

    Blue–green light passes through the crystal.

  4. Step 4

    Modifiers

    Mn³⁺ adds violet; Fe shifts toward green or darkens.

  5. Step 5

    Perceived colour

    Neon blue to green, depending on balance and cut.

References

  1. Study of optical absorption spectroscopy of Cu, Mn and Fe in tourmaline. Peer-reviewed mineralogical journal.Citation to be verified
  2. Reference text on tourmaline-supergroup mineralogy (elbaite and related species). Academic publisher.Citation to be verified

Author

Paraiba Ethiopia Editorial Team

The editorial team researches and writes Paraiba Ethiopia’s educational content on copper-bearing tourmaline, prioritising laboratory nomenclature and published gemological literature over trade claims.

Technical reviewer (assignment pending)

Independent gemological reviewer

Placeholder. A qualified gemologist will be named here once technical review of this page is complete. Until then, treat technical statements as editorially prepared but not yet independently reviewed.

First published 1 October 2026. Read our editorial policy

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