Gem library
Tourmaline
The gem of mixed colours, from pink to Paraíba
Gem tourmaline is the chameleon of the mineral world: it exists in every colour, sometimes several within one crystal. Its Paraíba variety, coloured by copper and discovered in Brazil in 1989, is one of the most expensive gems per carat on the planet.
- Hardness (Mohs)
- 7 – 7.5
- Density
- 3.01 – 3.11
- Crystal system
- Trigonal
- Refractive index
- 1.614 – 1.666
- Cleavage
- Very imperfect
Mineralogical identity
- Family
- Silicates — cyclosilicates, tourmaline group
- Species
- Elbaite
- Variety
- Rubellite, verdelite, indicolite, Paraíba, watermelon
- Chemical formula
- Na(Li,Al)₃Al₆(BO₃)₃Si₆O₁₈(OH)₄
- Crystal system
- Trigonal (rhombohedral)
- Classification
- Semi-precious stone
- Rarity
- Rare
- Indicative price
- €30 – 800/ct (Paraíba: €5,000 – 50,000/ct)
Etymology
From the Sinhalese turamali or toramalli, «stone of mixed colours» — Dutch merchants brought back parcels from Ceylon in which the colours were indistinguishable.
Physical & optical properties
- Hardness (Mohs)
- 7 – 7.5
- Density
- 3.01 – 3.11
- Refractive index
- 1.614 – 1.666
- Birefringence
- 0.018 – 0.040
- Cleavage
- Very imperfect
- Fracture
- Conchoidal to splintery
- Lustre
- Vitreous
- Diaphaneity
- Transparent to translucent
- UV fluorescence
- Weak
- Pleochroism
- Distinct
- Colours
- pink, green, blue, multicoloured, red, yellow
Formation, geology & history
Paraíba, a 1989 revolution
In 1989, in the Brazilian state of Paraíba, the prospector Heitor Dimas Barbosa uncovered, after five years of digging, a tourmaline of a neon blue-green never seen before, coloured by copper and manganese — a chemistry new to elbaite. The deposit was tiny and quickly exhausted, driving prices up to 50,000 dollars a carat for the best stones. In 2001 and then 2005, cuprian tourmalines were found in Nigeria and Mozambique: less saturated but far more plentiful, they have kept Paraíba accessible in small sizes. Whether a Mozambican tourmaline may legitimately be called Paraíba occupied laboratories for years; the accepted definition is chemical, not geographic.
A palette without equal
Each colour has its name: rubellite for pink-red, verdelite for green, indicolite for blue, dravite for brown, achroite for colourless. Zoned crystals are a speciality of the species: watermelon tourmaline shows a pink core wrapped in a green rind, revealed in spectacular cross-slices; bicolour crystals change hue along their axis. That zoning comes from successive chemical changes during growth in pegmatites. Its pleochroism is strong: a green tourmaline can look almost black along the c axis, which forces the lapidary to orient the table perpendicular to that axis.
Cutting and market
Tourmalines grow as long prisms, which favours elongated cuts: emerald, baguette, oval. The cutter's main challenge is managing pleochroism while keeping weight on often narrow crystals. Intense rubellites from Madagascar and Nigeria, chromian verdelites and clean bicolours are the most sought after alongside Paraíba. The commonest treatment is light heating, which lightens overly dark tourmalines; irradiation also exists on pink stones. A significant share of rubellites are fissured and sometimes resin-filled — worth checking.
How to recognise it
- Marked pleochroismRotate the stone: the colour darkens clearly along the prism axis. Few gems have pleochroism so visible to the naked eye.
- Needle and veil inclusionsFine parallel channels and irregular veils, called trichites, are typical of tourmaline.
- Lengthwise striations on roughThe fluted prism with a rounded triangular section is an immediate morphological signature.
Imitations, treatments & confusions
- Coloured glassBubbles, no pleochroism or birefringence, a softer lustre. Very common as an imitation of rubellite.
- Synthetic tourmalineIt exists but remains rare and costly to produce, so it is little present on the market — unlike synthetic ruby or sapphire.
- Dubious ParaíbaAbusive Paraíba labels are frequent. Only a chemical analysis confirming the presence of copper justifies the name; demand a certificate above a few hundred euros.
Deposits & origins
Brazil (Minas Gerais: rubellites, verdelites, and the Paraíba of São José da Batalha), Mozambique and Nigeria (African Paraíba), Madagascar, Afghanistan (Kunar), Pakistan, Nigeria, United States (California, Maine), Namibia
Care & precautions
- Warm soapy water and a soft brush, dried carefully.
- Avoid ultrasonic cleaning on rubellites, which are often fissured: vibration propagates fractures and drives out filling resin.
- Sensitive to thermal shock despite good hardness: do not move it abruptly from hot to cold.
- Intense sun can alter some irradiated pink tourmalines. Individual storage recommended.
Traditions & crystal healing
- Chakras
- Varies with colour
- Zodiac signs
- Libra · Leo · Aquarius
- Element
- Varies
- Month
- October (secondary)
Tradition assigns each colour a domain: rubellite to the heart and passion, verdelite to regeneration, indicolite to speech, watermelon to reconciling opposites. Its genuine pyroelectric property has fed its reputation as an «active» stone, able to exchange with its wearer.
The virtues described here belong to tradition and cultural heritage. They are in no way medical advice and never replace a consultation.
Frequently asked questions
What is a Paraíba tourmaline?
An elbaite coloured by copper, of a characteristic neon blue-green. Discovered in Brazil in 1989, then found in Nigeria and Mozambique. The definition is chemical: what counts is the presence of copper, not the geographic origin.
Why does my tourmaline look darker from one angle?
That is its pleochroism, very marked in this species: absorption differs along the crystal axes. A good lapidary orients the table perpendicular to the c axis to minimise the effect.
Are tourmalines treated?
Often: light heating to lighten dark stones, sometimes irradiation on pink ones, and resin filling on fissured rubellites. Heating is accepted; filling must be declared.