TOURMALINE

Green tourmaline and diamond ring

Species:  Tourmaline
​​Mohs Hardness:  7 to 7.5 out of 10
Color:  Nearly all colors
RI:  1.624 to 1.644 (+/-0.005)
Birefringence:  Usually 0.018 to 0.020
SR/DR/AGG:  DR
Clarity Type:  Type I - Green, Type III - Pink & Watermelon, Type II - All Other Colors
Optic Character:  Uniaxial negative
Pleochroism:  Medium to strong, usually two tones of the gem's body color.
Spectrum:  Varies
Fluorescence:  Varies
SG:  3.06 (+0.20 / -0.06)
Routine Treatments:  None
Additional Enhancements:  Irradiation, heating, coating

SHOP TOURMALINE JEWELRY

Tourmaline Facts

Paraíba tourmaline and diamond ring

Tourmaline is a very attractive gem that occurs in nearly every color.

Its name is derived from the word toramalli, which means "mixed gems" in Sinhalese, one of the languages spoken in Sri Lanka.

In 1554, Spanish conquistador Francisco Spinoza discovered green tourmaline crystals during a Brazilian expedition, which he mistook for emerald.  It wasn't until the 1800s that mineralogists finally identified tourmaline as its own species.

Fun Fact:  Tourmaline is both pyroelectric and piezoelectric, meaning it is a gem that becomes electrically charged when heated or squeezed!

While tourmaline occurs in many different colors, it can also occur in bicolor or tricolor crystals.  Watermelon tourmaline is an example of a tricolor tourmaline that is often cut into slices, showing off its unique coloring.

Paraíba tourmalines are the most valuable type of tourmaline and are known for their intense, vividly-saturated blue to violetish blue hues.
   
Tourmaline is an October birthstone and is the 8th wedding anniversary gemstone.

Tourmaline Varieties

PARAÌBA TOURMALINE

​
COLOR
​Intense, vividly-saturated blue to violetish blue caused by copper impurities.

MAGNIFICATION
Thread-like liquid and gas inclusions (trichites), mirror-like gas-filled fractures, and color zoning.

SPECTRUM
Not diagnostic but may show a broad area of absorption starting at 600nm.

FLUORESCENCE
Inert or weak to moderate bluish white under LW ultraviolet light.
(Red fluorescence is not Paraíba.)

RUBELLITE TOURMALINE

​
COLOR
Deep pink to red to purplish red.

MAGNIFICATION
Thread-like liquid and gas inclusions (trichites), mirror-like gas-filled fractures, color zoning, needles, crystals, liquid inclusions, and growth tubes.

SPECTRUM
Not Diagnostic

FLUORESCENCE
​Variable

WATERMELON TOURMALINE

COLOR
Strong color zoning, often in alternating shades of red, white and green.

MAGNIFICATION
Color zoning, thread-like liquid and gas inclusions (trichites), and mirror-like gas-filled fractures.

SPECTRUM
Not Diagnostic

FLUORESCENCE
Variable

Tourmaline Gallery

All photos courtesy of Scott Papper, GIA GG, AJP, CMA (NAJA)

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