Tourmaline: The Rainbow Gemstone – A Comprehensive Guide

Tourmaline vs. sapphire: Which holds value better?

Introduction

Tourmaline, known as “碧璽” (Bìxǐ) in Chinese and historically referred to as “避邪璽” (Bìxié xǐ, “evil-repelling seal”), is one of nature’s most colorful gemstones. While rarely mentioned in early Chinese texts, it gained prominence during the Qing Dynasty when imported from “比耶國” (possibly Burma or Sri Lanka). The Qing Dynasty Annals documented its use in imperial seals, believed to ward off misfortune. Today, tourmaline’s vibrant hues and unique properties make it a favorite among gemologists and collectors alike.

Physical & Chemical Properties

Tourmaline is a complex borosilicate mineral with the chemical formula Na(Li,Al)₃Al₆(BO₃)₃Si₆O₁₈(OH)₄. Key characteristics include:

Hardness: 7–7.5 on the Mohs scale (suitable for daily wear).
Density: 3.0–3.2 g/cm³.
Luster: Vitreous; transparent to opaque.
Crystal System: Trigonal, often forming elongated prisms with striations.
Piezoelectricity: Generates electricity under pressure (used in early scientific instruments).

Color Varieties & Value

Tourmaline’s name derives from the Sinhalese turmali (“mixed gems”), reflecting its spectrum of colors:

1. Paraíba Tourmaline

Color: Neon blue-green (copper-doped).
Rarity: Mined in Brazil; the most expensive variety (~$10,000/carat).

2. Rubellite (紅碧璽)

Color: Deep pink to red (resembles ruby).
Key Trait: Retains color in all lighting (unlike pink sapphire).

3. Watermelon Tourmaline

Color: Green outer layer with pink core (resembles watermelon).
Historic Use: Qing Dynasty snuff bottles.

4. Dravite (Brown) & Indicolite (Blue)

Dravite: Yellow-brown; common in Tibet.
Indicolite: Rare blue; favored by Art Nouveau jewelers.

Grading Criteria:

Color Intensity: Vivid hues (e.g., “double peach red” 雙桃紅) command premiums.
Clarity: Eye-clean stones are ideal, but inclusions may create cat’s-eye effects.

Historical & Cultural Significance

Qing Dynasty: Empress Dowager Cixi adored pink tourmaline, popularizing it in hairpins and rings.
Global Lore:
Egypt: Believed to journey from Earth to sun via rainbows.
Europe: 18th-century scientists used it in pressure gauges.

Global Sources

Primary Deposits:
Brazil (Minas Gerais, Paraíba).
Afghanistan (pink and green).
China (Xinjiang’s Altai Mountains—historical source for Qing artisans).
Synthetics: Lab-grown versions exist but lack value.

Craftsmanship & Modern Uses

Jewelry: Faceted for rings, carved into “福” (fortune) pendants.
Technology: Still used in high-precision pressure sensors.

Cutting Tips:

Pleochroism: Cut to showcase the deepest color (e.g., table parallel to crystal length for rubellite).
Inclusion Art: Needle-like rutile creates “horsetail” patterns in cabochons.

Why Tourmaline?

Diversity: Over 30 color varieties—no two stones are alike.
Metaphysical Claims: Allegedly balances energy (though unproven).

Tourmaline vs. sapphire: Which holds value better? Explore tourmaline’s kaleidoscope at VirtuCasa.com.

Tourmaline: The Rainbow Gemstone – A Comprehensive Guide