A Single 0.82ctct IFNatural Baguette Cut Greenish Blue Tourmaline Gemstone!!!
Wonderful and Very Pretty Little Stone!!!
Gemstone Properties:
Size = 6.5 x 6.1 x 3.7mm
Weight = 1.37ct
Shape/Cut = Baguette
Color = Greenish Blue
Clarity = IF
Treatment = None
Origin = Unknown
Tourmaline Gemological Properties:
Chemical Formula: | Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH) Elbaite: Na(Li1.5,Al1.5)Al6Si6O18(BO3)3(OH)4 |
Crystal Structure: | Trigonal; long crystals with a triangular cross-section and rounded sides, definite striation parallel to axis |
All colours | |
7 to 7.5 on the Mohs scale | |
1.614 to 1.666 | |
2.82 to 3.32 | |
Indistinct | |
Transparency: | Transparent to opaque |
Double Refraction or Birefringence: | -0.014 to -0.032 |
Lustre: | Vitreous |
Fluorescence: | Weak or none |
Tourmaline Gemstone Information
Tourmaline is the gemological name for an important group of complex gem-quality boron silicate minerals. Tourmaline gemstones can be found in all colors of the rainbow. Owing to its wide range of color availability, tourmaline is considered to be one of today's most versatile gemstones. Its name is thought to be derived from the Sinhalese word, "turamali", which means "stone with various colors" in reference to its extreme versatility. Tourmaline was first thought to be used as a gemstone around the 1500s, but distinct mineral species were not actually described until the 1800s. In 1875, George Kunz, an American mineral collector, introduced green tourmaline from the Mount Mica mine in Maine, USA to Tiffany & Co., which sparked an interest in tourmaline and led to its popularity (along with other semi-precious gemstones) on the mainstream jewelry market.
The major tourmaline species include dravite, uvite, schorl, liddicoatite and elbaite. Schorl is the most common variety, making up nearly 95% of all tourmaline deposits, but it is not often desired as a gemstone. Most tourmaline gemstones are varieties of the elbaite family. Since tourmaline consists of a very large group of related gemstones, most tourmaline is traded under very color-specific varietal names. Some of the more popular trade names include pink-red 'rubellite', blue-green 'paraiba', blue 'indicolite' and multicolored 'watermelon tourmaline'. Lesser-known trade names include colorless 'achroite', green 'verdelite' and 'chrome tourmaline'. Like sapphire, descriptive names such as 'yellow tourmaline' or 'pink tourmaline' are also commonly used to market fancy-colored tourmaline gemstones.
Identifying Tourmaline
Tourmaline is a boron silicate mineral often containing traces of aluminum, iron, magnesium, sodium, lithium, copper and potassium. Tourmaline crystals form in the trigonal crystal system and can be distinguished by their distinct three-sided triangular prisms. Tourmaline has very distinct gemological properties which can help identify it from other similar colored gemstones. Tourmaline has superior hardness (7 to 7.5 on the Mohs scale), poor cleavage and strong pleochroism. Tourmaline is known to exhibit unique pyro-piezoelectric properties, which means crystals can produce and hold an electrical charge when subjected to mechanical stress, pressure or extreme temperature fluctuations, earning it the nickname of the 'electric stone'. When tourmaline crystals are rubbed, friction can cause static and when held over dust or ash, the static can attract particles, which is why it is sometimes referred to as the 'Ceylonese (Sri Lankan) magnet'.
Tourmaline; Origin and Gemstone Sources
Tourmaline is found in pegmatite and alluvial deposits all over the world. Tourmaline is the national gemstone for the United States, where it has been mined for centuries. In fact, up until the early 1900s, the United States was considered the primary source for fine tourmaline. Today, the most significant tourmaline deposits come from Minas Gerais and Bahia, Brazil. Other notable tourmaline sources include Afghanistan, Australia, Burma (Myanmar), India, Italy, (Elba) Madagascar, Malawi, Mozambique, Namibia, Nepal, Nigeria, Pakistan, Russia, Sri Lanka, Switzerland, (Tessin) Tanzania, the United States (California and Maine), Zaire, Zambia and Zimbabwe.
Tanzania is known to produce fine emerald-green chrome dravite tourmaline, and in the late 1990s, a copper-bearing blue paraiba tourmaline was discovered in Nigeria; shortly thereafter, another deposit of a copper-bearing paraiba tourmaline was discovered in Mozambique. Both of Africa's paraiba tourmaline deposits were not as intensely colored as Brazilian materials. Zambia is known for producing fine red rubellite and yellow canary tourmaline, while Afghanistan is famed for producing fine green verdelite and rare blue indicolite.
Buying Tourmaline and Determining Tourmaline Gemstone Value
Tourmaline Color
Tourmaline can occur in a wide range of colors from colorless to black. Colorless tourmaline is considered to be the rarest, but it is also the least valuable tourmaline. Black tourmaline is actually the most common color occurrence. Most tourmaline gemstones display two or more colors in a single stone (or two tones of the same color). Tourmaline crystals that exhibit green on one end and pink to red on the other, with a band of white in the middle are marketed as 'watermelon tourmaline'. Tourmaline exhibits strong pleochroism, which means its crystals can exhibit different colors depending on the angle from which they are viewed. Most red, pink and brown to yellow tourmaline is colored by manganese, while iron and titanium can result in greenish to bluish-black colors. Lithium impurities can result in just about every color, including blue, green, red, yellow and pink. The rare emerald-green chrome tourmaline is colored by chromium (and sometimes vanadium). Many pink tourmaline crystals obtain their color though a natural irradiation process. Cat's eye tourmaline is typically green or pink in color, although it can also occur in other rarer colors too. The most valuable and rare tourmaline is neon green-blue paraiba tourmaline, which is colored by copper. Other valuable color combinations include purplish-red 'rubellite' and blue 'indicolite'. When buying tourmaline, color intensity and saturation are the most important factors.
Tourmaline Clarity and Luster
Tourmaline is typically transparent to translucent. Opaque material is common for cat's eye tourmaline and schorl. According to GIA, most tourmaline is 'Type II' material in regard to clarity, which means tourmaline is often included. The level of inclusions can vary depending on the type of tourmaline, with some colors being more heavily included than others. Green tourmaline is often eye-clean, while blue, red and pink tourmaline, including rubellite, paraiba and watermelon tourmaline, are almost always found with significant inclusions. Rubellite, paraiba and watermelon tourmaline are considered to be Type III clarity gems. Cat's eye tourmaline is usually translucent to opaque and owes its chatoyancy to thin needle-like inclusions. When cut and polished, tourmaline exhibits a vitreous to sometimes slightly resinous luster.
Tourmaline Cut and Shape
Tourmaline is often cut into long rectangular bar shapes because of its elongated crystal habit. However, tourmaline is also available in various traditional and fancy shapes and a range of cutting styles. Due to the strong pleochroism of tourmaline, lighter colored tourmaline is typically oriented with the table facet perpendicular to the main axis, in order to display the richest hue. Conversely, darker stones are usually cut with the table parallel to the main axis. Rare cat's eye tourmaline is cut en cabochon to best display the desirable cat's eye chatoyancy. Watermelon tourmaline is often cut into slices to best exhibit its characteristic and attractive color zoning.
Tourmaline Treatment
Most tourmaline is completely untreated. However, some stones may be heated to improve color and clarity. Yellow, pink and red varieties of tourmaline may be irradiated to enhance color, although irradiation is nearly impossible to detect and does not normally affect value. Heavily included rubellite and paraiba tourmaline may be clarity enhanced.
Tourmaline Gemstone jewellery Care and Cleaning
Tourmaline gemstones are quite tough and durable. Due to their pyro-piezoelectric properties, tourmaline gemstones do need to be wiped down frequently as they tend to attract more dust and particles than most other gemstones. To clean your tourmaline gems, simply use warm soapy water and a soft cloth. Be sure to rinse well to remove soapy residue. As with most gemstones, ultrasonic cleaners and steamers are not recommended. Tourmaline gemstones should not be exposed to sudden changes in temperature. Always remove any jewellery or gemstones before exercising, cleaning or engaging in harsh physical activities such as sports. Store tourmaline gemstones away from other gemstones to avoid scratches. It is best to wrap gemstones in soft cloth or place them inside a fabric-lined jewellery box.
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