Tourmaline
Tourmaline
Tourmaline represents a large group of related mineral species that exhibit many unusual optical and physical properties. The tourmaline group consists of buergerite, chromdravite, dravite, elbaite, feruvite, liddicoatite, rossmanite, schorl and uvite. The Elbaite series includes rubellite, indicolite, paraíba, and watermelon tourmaline. Chemically more complex than most minerals, tourmaline exhibits a substantial range of colors and varieties. Some varieties exhibit two or more colors in the same stone.
General Information
Tolerance:(+0.011/-0.009)
LWUV: Inert to weak red to violet
Tourmaline Colors
-
Bi-color -
Black -
Blue -
Blue -
Brown -
Colorless -
Gray -
Green -
Green -
Green -
Green -
Multi-color -
Orange -
Pink -
Pink -
Purple -
Purple -
Red -
White -
Yellow
Tourmaline Spectra
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.
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
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.
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.
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.
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.
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.
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.
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.
We acknowledge 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; Russian Federation; Sri Lanka; United States of America; Madagascar; Zambia; Kenya; Thailand; Congo; India; Sweden; Mozambique; Pakistan; Morocco; Unknown; China; Namibia; 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 - 7.5. It's easy to wear and easy to care for. Avoid steam or ultrasonic cleaners and avoid sudden temperature changes. Tourmaline will respond well to warm, sudsy water, a thorough rinse and a soft-cloth dry. Avoid harsh chemicals; use only gentle soap.
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.
Species/Variety
Cat's Eye Tourmaline
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.
LWUV: Variable
Paraiba
Paraíba tourmalines are copper bearing elbaite tourmaline that are neon to electric blue, intense green, and vivid purple to violet in color. Heitor Dimas Barbosa headed up a team of 13 garimpeiros in search for tourmaline in 1982 outside the village of São José da Batalha in north central Paraíba State, Brazil. The first Paraíba tourmaline was found at the Batalha Mine in 1987 and the gemstone first appeared at the Tucson gem shows in 1990. Cuprian tourmaline was later found in other locations in Brazil, Nigeria, and Mozambique that also bear the name Paraíba tourmalines. The blue and bluish green colors are due to Cu2+. The additional presence Mn3+ causes color absorption in the spectra and produces violet to purple colors. Heat can be used to intensify color and included stones are fracture filled with oil or polymers to improve clarity.
LWUV: Variable
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.
LWUV: Variable
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.
LWUV: Inert
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.
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.
LWUV: Variable Pink: inert to very weak red to violet
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