Natural Tourmaline: Complete Guide for Trade, Jewelry, and Collections

This comprehensive guide provides everything you need to know about natural tourmaline, for trade partners, jewelers, and collectors alike.

Overview

Natural tourmaline is a diverse gemstone group known for its remarkable color variations, ranging from deep greens and blues to vivid pinks and yellows. With a hardness of 7 to 7.5 on the Mohs scale, tourmaline is durable and suitable for a variety of jewelry applications. Its unique pleochroism allows it to exhibit different colors when viewed from different angles, adding to its allure. As a popular choice among jewelers and collectors alike, understanding tourmaline's characteristics, sources, and market dynamics is crucial for anyone involved in its trade or collection.

Physical Properties and Specifications

  • Chemical Composition: Varied; common formulas include Na(Li,Al)₄(Al,Fe,Mn)₃Si₆O₁₈(BO₃)₃(OH)₄

  • Hardness: 7 - 7.5 on the Mohs scale

  • Crystal System: Hexagonal

  • Refractive Index: 1.620 - 1.700

  • Specific Gravity: 2.83 - 3.20

  • Pleochroism: Strong, exhibiting different colors depending on the angle of view

  • Fluorescence: Generally inert, but some specimens may show weak fluorescence

  • Cleavage/Fracture: Indistinct cleavage, conchoidal fracture

Color and Quality Classifications

Available Color Ranges

  • Primary hues: Pink, green, blue, yellow, red, and black

  • Secondary modifications: Brown, gray, and multicolored (bicolor and tricolor)

  • Tone and saturation ranges: Light to dark tones with vivid saturation

  • Premium colors: Deep pink, rich green, and intense blue

  • Commercial grades: Light shades and less saturated colors

Clarity Characteristics

  • Typical inclusion types: Needle-like inclusions, color zones, and internal fractures

  • Clarity grading standards: Eye-clean to included

  • Source-specific features: Unique inclusions that may indicate origin

  • Eye-clean criteria: No visible inclusions to the naked eye

Source Locations and Material

Historic sources

  • Brazil, Afghanistan, Sri Lanka, and Madagascar

Current production

  • Significant production is currently from Brazil, Nigeria, and Mozambique.

Source-specific characteristics

  • Each location imparts distinct characteristics in color and clarity.

Production trends

  • Increasing demand for tourmaline has led to rising prices, especially for high-quality specimens.