Blue tourmaline, also known as indicolite, is a highly prized gemstone among collectors and enthusiasts. Its captivating blue hues, ranging from deep navy to light sky blue, make it a sought-after gem in the jewelry world. However, with its increasing popularity, the market has seen a rise in imitations and synthetic counterparts. This article will guide you through the process of identifying authentic blue tourmaline stones, ensuring that your purchase is genuine and of high quality.
Understanding Blue Tourmaline
What is Blue Tourmaline?
Blue tourmaline, or indicolite, is a variety of the tourmaline family, known for its unique crystal structure and wide range of colors. The blue color in tourmaline is caused by trace amounts of iron and sometimes copper within the crystal lattice. These stones are typically found in Brazil, Nigeria, and Afghanistan, with Brazil being the primary source of high-quality blue tourmalines.
The Importance of Authenticity
Authentic blue tourmaline stones are valued for their natural beauty and rarity. Fake or synthetic stones lack the unique characteristics that make blue tourmaline special. Identifying genuine blue tourmaline ensures you are investing in a true gem that retains its value and aesthetic appeal.
Physical Characteristics of Blue Tourmaline
Color
The most striking feature of blue tourmaline is its color. Authentic blue tourmaline exhibits a range of blue shades, from light blue to deep blue. The color should be vivid and evenly distributed throughout the stone. Natural stones may show slight variations in color intensity, which is a sign of authenticity.
Clarity
Blue tourmaline stones typically have good clarity, though inclusions are common. Inclusions are natural imperfections that occur during the crystal’s formation. These can include needle-like structures, liquid-filled cavities, or other mineral inclusions. While some inclusions are acceptable, stones with fewer inclusions are generally more valuable.
Cut
The cut of blue tourmaline can greatly affect its appearance and value. Authentic blue tourmaline is often cut in a way that maximizes its color and brilliance. Common cuts include oval, round, emerald, and cushion cuts. The quality of the cut should enhance the stone’s natural beauty without compromising its structural integrity.
Hardness
Tourmaline has a hardness of 7 to 7.5 on the Mohs scale, making it relatively hard and durable. This hardness makes blue tourmaline suitable for various types of jewelry. When identifying authentic blue tourmaline, ensure the stone is not easily scratched, which would indicate a softer material and potential imitation.
Testing Blue Tourmaline for Authenticity
Visual Inspection
Color Consistency
Examine the stone under different lighting conditions. Authentic blue tourmaline should display consistent color without significant dark or light patches. Synthetic stones may have unnatural color zoning or uneven distribution of color.
Inclusions
Using a loupe or microscope, inspect the stone for natural inclusions. As mentioned, authentic blue tourmaline may have inclusions, but they should look natural. Synthetic stones often have gas bubbles or other artificial inclusions that appear different from natural ones.
Refractive Index
Tourmaline has a specific refractive index (RI) ranging from 1.624 to 1.644. Using a refractometer, you can measure the stone’s RI. Authentic blue tourmaline will fall within this range. Be cautious of stones with an RI significantly outside this range, as they may be imitations.
Dichroism
Blue tourmaline exhibits strong dichroism, meaning it can show two different colors when viewed from different angles. This is due to the stone’s crystal structure. To test for dichroism, use a dichroscope or simply rotate the stone under a light source. Authentic blue tourmaline will display noticeable color changes.
Thermal Conductivity
Tourmaline has low thermal conductivity compared to diamonds and other synthetic materials. A thermal conductivity tester can help differentiate between authentic tourmaline and imitations. Authentic tourmaline will show low thermal conductivity, unlike synthetic stones that may exhibit higher conductivity.
Specific Gravity
Tourmaline has a specific gravity (SG) of 3.06 to 3.25. Using a hydrostatic balance or a similar device, you can measure the stone’s SG. Authentic blue tourmaline should fall within this range. Stones with significantly different SG values may be imitations.
Professional Verification
Gemological Laboratory
For absolute certainty, consider sending your blue tourmaline to a reputable gemological laboratory. Laboratories such as the Gemological Institute of America (GIA) or the American Gemological Laboratories (AGL) can provide a detailed report on the stone’s authenticity and quality.
Certification
A certified blue tourmaline comes with a grading report from a recognized gemological laboratory. This report includes information on the stone’s color, clarity, cut, and authenticity. Purchasing certified stones adds a layer of assurance to your investment.
See Also: Astrological Benefits of Black Tourmaline
Common Imitations and How to Spot Them
Synthetic Blue Tourmaline
Synthetic tourmalines are created in laboratories and can closely mimic the appearance of natural stones. However, they often lack natural inclusions and have a more uniform color. Using the tests mentioned above, such as refractive index and dichroism, can help distinguish synthetic stones from authentic blue tourmaline.
Glass Imitations
Glass imitations are relatively easy to spot with careful inspection. They often have gas bubbles and a lower hardness than genuine tourmaline. A scratch test can reveal a glass imitation, as it will scratch more easily than authentic tourmaline.
Other Gemstones
Some blue gemstones, like blue topaz or aquamarine, can be mistaken for blue tourmaline. Comparing the specific gravity, refractive index, and dichroism of these stones can help in accurate identification. Blue topaz, for instance, has a higher refractive index and different dichroic properties compared to blue tourmaline.
Care and Maintenance of Blue Tourmaline
Cleaning
To maintain the beauty of your blue tourmaline, clean it regularly with mild soap and warm water. Avoid using harsh chemicals or ultrasonic cleaners, as they can damage the stone. Gently scrub with a soft brush and rinse thoroughly.
Storage
Store your blue tourmaline separately from other gemstones to prevent scratches. Use a soft pouch or a lined jewelry box to protect the stone from physical damage.
Handling
While tourmaline is durable, it’s still susceptible to damage from hard knocks or extreme pressure. Handle your blue tourmaline jewelry with care and avoid wearing it during activities that could result in impact or abrasion.
Conclusion
Identifying authentic blue tourmaline requires a combination of careful observation and scientific testing. By understanding the physical characteristics, performing basic tests, and seeking professional verification, you can confidently determine the authenticity of blue tourmaline stones. Whether you are a collector, jeweler, or enthusiast, these guidelines will help ensure that your blue tourmaline purchase is genuine and valuable. Remember, the beauty of blue tourmaline lies in its natural origins and unique properties, making it a truly remarkable gemstone to own and cherish.
