Tourmaline

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Once proposed to be the national gemstone of the United States, tourmaline is found all over the world and in a variety of colors. Tourmaline is the most colorful of all gemstones because, according to an ancient Egyptian legend, it passed through a rainbow on its journey to Earth and brought all of the colors of the rainbow with it. Tourmaline is a mineral group comprised of multiple species of complex borosilicates. Lovingly referred to by mineralogists as the garbage can mineral, its crystal structure allows for the incorporation of a wide range of elements, many of which cause the stunning color varieties and spectacular zoning of tourmaline, including copper, manganese, iron, and titanium. Major tourmaline species include liddicoatite, dravite, uvite, schorl, and elbaite.

Tourmaline Polished
Tourmaline Classification
Common Name Tourmaline
Species Tourmaline
Tourmaline Optical Properties
Transparency Transparent - Opaque
Dispersion Strength: Weak Fire Value: 0.017
Refractive Index 1.624-1.644
Tolerance:(+0.011/-0.009)
Birefringence 0.018-0.040
Optic Character Uniaxial
Optic Sign Negative
Polariscope Reaction Doubly Refractive (DR)
Fluorescence SWUV: Inert to weak red to violet
LWUV: Inert to weak red to violet
Pleochroism Dichroic, moderate to strong, varying shades of body color
Tourmaline Characteristic Physical Properties
Hardness 7-7.5
Streak White
Specific Gravity 3.000-3.260 Range:0.2/-0.06 Typical:3.060
Toughness Fair
Inclusions Green tourmaline is a type I clarity stone. Blue, purple, red, orange, yellow and bi-color or parti-colored tourmaline is a type II clarity stone. Red and watermelon tourmaline are type III clarity stones. Tourmaline might contain tube-like 2-phase inclusions running parallel to crystal's principle axis, film-like, irregular or long and thin liquid inclusions, angular thin reflective inclusions, gas inclusions in net-like pattern, parallel oriented hollow tubes, needles.
Luster Vitreous
Stability Very Good
Fracture Conchoidal, Uneven
Cleavage Poor, in two directions
Tourmaline Chemistry & Crystallography
Chemical Name complex boro-silicate of Al, Mg and Fe
Chemical Formula (Ca,K,Na)(Al,Fe,Li,Mg,Mn)3(Al,Cr,Fe,V)6(BO3)Si6O18(OH,F)4
Crystal System Trigonal
Chemistry Classification Silicate

Tourmaline Colors

  • Purple Tourmaline Purple
  • White Tourmaline White
  • Red Tourmaline Red
  • Orange Tourmaline Orange
  • Multi-color Tourmaline Multi-color
  • Gray Tourmaline Gray
  • Black Tourmaline Black
  • Pink Tourmaline Pink
  • Blue Tourmaline Blue
  • Brown Tourmaline Brown
  • Bi-color Tourmaline Bi-color
  • Purple Tourmaline Purple
  • Yellow Tourmaline Yellow
  • Green Tourmaline Green
  • Green Tourmaline Green
  • Green Tourmaline Green
  • Pink Tourmaline Pink
  • Blue Tourmaline Blue

Tourmaline Spectra

Tourmaline Spectra
TOURMALINE Greenish blue

Color due to iron. The pale greenish blue tourmaline used for this spectrum shows very weak absorption with a faint narrow iron band where the blue merges to the green at 497nm. Broader bands are also seen in the green-yellow area centered at 560nm. and 580nm. Transmission fades in the orange as absorption sets in beyond 620nm.

Tourmaline Spectra
TOURMALINE (Unpolarized)

Color due to manganese. The broad band in the green centered at about 525nm. is a common feature of most pink and red tourmalines. Here it is so strong that the sharper line often seen within it at 537nm. is obscured. However, there is evidence of the faint lines at 450nm.and 458nm. normally associated with paler red and pink varieties

Tourmaline Spectra
Tourmaline (Unpolarized) Brown

Color due to iron and manganese. The spectrum of this reddish-brown tourmaline shows characteristics of the spectra seen in the red, pink and dark brown varieties. Here we see a broad moderate absorption centered at 497nm., usually attributed to iron, extending well into the blue and green on each side. Careful observation within this broad absorption will reveal narrower bands in the deep blue at 450nm. and 458nm. and also in the green at 525nm. and 537nm. These bands may also be seen in pink tourmaline where they are attributed to manganese.

Tourmaline Spectra
TOURMALINE (ω ray)

Color due to manganese. The broad band in the green centered at about 525nm. is a common feature of most pink and red tourmalines, faint lines at 450nm.and 458nm. In the direction of the o ray, the broad absorption intensifies to produce the deeper color of the dichroism making the lines in the blue more difficult to detect.

Tourmaline Spectra
TOURMALINE (ω ray) Brown

Transmission of the ordinary ray is considerably reduced by the intensity of the broad absorption band which covers most of the blue and green. Bands within this area are now obscured but a window of transmission in the deep blue enhances observation of the two lines at 450nm. and 458nm. Under the polarizing filter the stone appears a brownish orange in this direction.

Tourmaline Spectra
TOURMALINE (ε ray)

Color due to manganese. The broad band in the green centered at about 525nm. is a common feature of most pink and red tourmalines, faint lines at 450nm.and 458nm. As the absorption in the green narrows and weakens the stone appears a paler red to indicate the e-ray and the lines in the blue are a little easier to resolve.

Tourmaline Spectra
TOURMALINE (ε ray) BROWN

The paler yellowish-brown extraordinary ray transmits much more light with a much subdued broad absorption centered in the blue - green area about 500nm. Only a vague indication is seen of the lines at 450nm. and 458nm.

Tourmaline Spectra
TOURMALINE Blue

Color due to iron. Blue tourmaline transmits very little red and although the main absorption lines are stronger in the ordinary ray this is often too dark to see them easily. Here the unpolarized spectrum shows a moderate narrow band at 497nm. and a weaker band to the long wave side of this at 515nm. A broader diffuse band is seen at 560nm. before general absorption sets in after 600nm.

Tourmaline Spectra
TOURMALINE Greenish blue

Color due to iron. In green and blue tourmaline, the first thing we generally notice is the poor transmission in the orange and red and in this unpolarized spectrum there is nothing beyond 605nm. Often absorption in the ordinary ray is too strong and no transmission is seen beyond about 570nm. Other bands contributing to the color of this tourmaline are a narrow one seen at 497nm. and two other wider diffuse bands centered at 560nm. and 585nm.

Jewelry Television acknowledges the significant scientific contributions of John S Harris, FGA to the study of gemstone spectra and with deep appreciation to him, acknowledges the use of his images and related notes about gemstones and their spectra in the educational materials on this website.

Alternate Names

Achroite, Bi-Color Or Parti-Colored, Chrome Tourmaline, Dravite, Elbaite, Fluor-Buergerite, Indicolite, Liddicoatite, Povondtaite, ParaBa Tourmaline, Rubellite, Schorl, Uvite, Verdelite, Watermelon

Countries of Origin

Tanzania, United Republic Of; Myanmar; Afghanistan; United States of America (the); Sri Lanka; Congo (the); Madagascar; Zambia; Kenya; Thailand; India; Sweden; Mozambique; Pakistan; Morocco; Unknown; China; Namibia; Russian Federation (the); Brazil; Mexico; South Africa; Australia; Nigeria

History

The word tourmaline comes from the ancient Sinhalese word, turamali which means "stone of many colors." We know that tourmaline is a gemstone that's found in a veritable rainbow of options. But how about a tourmaline that has that rainbow of colors within a single crystal? Multi-colored tourmaline is found in combinations like gold with pink and red, or green, gold and red. It's called by many names, parti-colored, bi-color, tri-color, and even watermelon in the case of the most often seen duo of pink and green! Whether you choose tourmaline with a single color, a stone with two colors or a stone with many colors, tourmaline is well worth owning. It may be called a myriad of things by experts. We jewelry lovers call it wonderful.

Care

Tourmaline is very wearable with a Mohs hardness of 7 - 7 ½. It's easy to wear and easy to care for. Avoid steam and ultrasonic cleaners for oiled or stabilized stones. Tourmaline will respond well to warm, sudsy water, a thorough rinse and a soft-cloth dry. Avoid harsh chemicals; use only gentle soap.

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Related Videos

More About Tourmaline

Ancient civilizations needed to explain the world in which they lived, very much as we do today. Without modern scientific tools, they had to find more fanciful explanations for earth's wonders. According to legend, tourmaline is found in many colors because it traveled along a rainbow and picked up its colors along the way. Tourmaline was a valued element in ancient medicine, especially in the Far East where it was believed useful as a remedy for all manner of illnesses.

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Species/Variety

Dravite

Dravite is the dark yellow to brown variety of tourmaline.It is named after a deposit in modern day Slovenia near the Drave river.

Dravite Tourmaline
Dravite Classification
Common Name Dravite
Dravite Optical Properties
Dispersion Strength: moderate fire Value: 0.017
Refractive Index 1.614-1.666
Birefringence 0.014-0.032
Fluorescence LWUV: Inert to weak
Pleochroism Dichroic, strong pale yellow to colorless and yellow, green, or brown
Dravite Characteristic Physical properties
Inclusions Dravite is a Type II clarity stone. Stones might have liquid and gas inclusions that are long and thin, reflective gas-filled fractures and color zoning.

Elbaite

The tourmaline family consists of at least 14 distinct minerals, but the variety elbaite accounts for nearly all gem-quality tourmaline. It was named as a result of the colored and colorless tourmalines found on the picturesque island of Elba off the western coast of Italy--history buffs know this island as the place where Napoleon Bonaparte was exiled in 1814. Although best known in shades of green and red, elbaite can also be blue, purple, yellow, or colorless. Notable varieties of elbaite include rubellite, green tourmaline, indicolite, watermelon tourmaline, Paraiba tourmaline and colorless.

Elbaite Tourmaline
Elbaite Classification
Common Name Elbaite
Elbaite Optical Properties
Dispersion Strength: moderate fire Value: 0.017
Refractive Index 1.614-1.666
Birefringence 0.014-0.032
Fluorescence SWUV: Inert
LWUV: Inert
Elbaite Characteristic Physical properties
Specific Gravity 2.9
Inclusions Green elbaite tourmaline stones are type I clarity stones.Blue, purple, orange, yellow and bi-color or parti-colored elbaite tourmalines are type II clarity stones.Stones might contain liquid and gas inclusions that are long and thin, reflective gas-filled fractures and color zoning.

Multi-Colored Tourmaline

Multi-colored tourmaline is a variety of tourmaline containing two or more colors displayed in one crystal.Green and pink is the most prevalent combination, but others are possible. Multi-colored tourmaline may be referred to as "bi-colored tourmaline" or "tri-colored tourmaline," etc.

Multi-Colored Tourmaline Tourmaline
Multi-Colored Tourmaline Classification
Common Name Multi-Colored Tourmaline
Multi-Colored Tourmaline Optical Properties
Dispersion Strength: moderate fire Value: 0.017
Birefringence 0.018-0.02
Fluorescence SWUV: Variable
LWUV: Variable
Multi-Colored Tourmaline Characteristic Physical properties
Inclusions Multi-colored tourmaline is Type II clarity stone. Stones will have two or more color zones. Stones might contain liquid and gas inclusions that are long and thin, reflective gas-filled fractures and color zoning.

Paraiba

When Paraiba tourmaline was first discovered in Brazil in the 1980's, the unusually intense "neon" or "electric" blues and greens set it apart from any other tourmaline previously known. The color of this gem ranges from intense emerald green through vivid Caribbean blue to a rich sapphire blue.Apart from its intense colors, another key feature of Paraiba tourmaline is its relative lack of extinction, best described as a lifeless area within a stone.

Paraiba Tourmaline
Paraiba Classification
Common Name Paraiba
Paraiba Optical Properties
Dispersion Strength: moderate fire Value: 0.017
Birefringence 0.018-0.02
Fluorescence SWUV: Variable
LWUV: Variable
Paraiba Characteristic Physical properties
Inclusions Paraiba tourmaline is a type II clarity stone. Stones might contain liquid and gas inclusions that are long and thin, reflective gas-filled fractures and color zoning.

Watermelon Tourmaline

Watermelon tourmaline is an interesting multi-colored elbaite variety. Gems are usually fashioned in thin polished slices to display the crystal's concentric color rings. If you use your imagination, the green represents the skin of the watermelon, white makes up the rind, and pink is the sweet fruit. Incredibly, the colors of watermelon tourmaline are 100% natural, a rare occurrence in nature that makes the gem highly collectible.

Watermelon Tourmaline Tourmaline
Watermelon Tourmaline Classification
Common Name Watermelon Tourmaline
Watermelon Tourmaline Optical Properties
Dispersion Strength: moderate fire Value: 0.017
Birefringence 0.018-0.02
Fluorescence SWUV: Variable
LWUV: Variable
Pleochroism Dichroic, medium to strong, varying shades of body color
Watermelon Tourmaline Characteristic Physical properties
Inclusions Watermelon tourmaline is Type II clarity stone. Color zoning with pink core and green edges. Stones might contain liquid and gas inclusions that are long and thin, reflective gas-filled fractures and color zoning.

Optical Phenomena

Cat's Eye

The term cat's eye, or chatoyancy, is used to describe a phenomenal optical property in gemstones, in this case tourmaline. The effect, when present, appears as a bright, narrow slit similar to the pupils in the eyes of your favorite feline. This phenomenon is caused by parallel fibrous or needle-like inclusions that interfere with the passage of light throughout the crystal, scattering and reflecting light back to the viewer as a thin line. Cat's eye tourmaline can occur in many colors but particularly in green and pink varieties.

Cat's Eye Tourmaline
Cat's Eye Classification
Common Name Cat's Eye
Cat's Eye Optical Properties
Dispersion Strength: moderate fire Value: 0.017
Birefringence 0.018-0.02
Fluorescence SWUV: Variable Pink: inert to very weak red to violet
LWUV: Variable Pink: inert to very weak red to violet
Pleochroism Dichroic, medium to strong variations of body color
Cat's Eye Characteristic Physical properties
Inclusions Cat's-eye tourmaline has Type III clarity. Stones has numerous parallel hollow tubes. The eye is less focused and harder to see than other cat's-eye stones. Stones might have liquid and gas inclusions that are long and thin, reflective gas-filled fractures and color zoning.
Tim Matthews

Author

Tim Matthews

Tim Matthews is President and Chief Executive Officer of Jewelry Television® (JTV), as well as a member of the company's Board of Directors. He oversees and leads all aspects of the company's powerful omni-digital retail platform that uniquely specializes in fine jewelry and gemstones. His passion for business and gemstones has led him to become a recognized expert in the field of gemology. He is a life member of the Gemmological Association of Great Britain (Gem-A) and has earned Gem-A's highest degrees, the Gemmology (FGA) and Diamond (DGA) diplomas. He is also a Graduate Gemologist (GG) of the Gemological Institute of America (GIA) and has also completed GIA's Graduate Diplomas in Diamonds, Colored Stones and Pearls. Under his leadership, JTV has become the leader in the sourcing and selling of color gemstones and jewelry.

This page was created on June 27, 2014.

This page was last edited on October 24, 2019.