How Can You Tell If Tanzanite is Real?

Choosing a genuine tanzanite gemstone can be a rewarding experience, especially given its stunning deep blue to violet hues and rarity. However, with the gemstone market flooded with imitations and synthetic stones, it’s essential for buyers and enthusiasts to learn how to distinguish real tanzanite from fakes. Understanding the key characteristics, testing methods, and reputable sources can help ensure you invest in an authentic piece that will retain its beauty and value over time.

How Can You Tell If Tanzanite is Real?

Determining the authenticity of tanzanite involves a combination of visual inspection, physical tests, and sometimes professional appraisal. Since tanzanite is a relatively soft gemstone (6.5 to 7 on the Mohs scale) and exhibits unique optical properties, these features can be used to differentiate genuine stones from imitations or synthetic versions.

Visual Inspection: Examining Color and Clarity

One of the first steps in identifying real tanzanite is closely examining its appearance. Authentic tanzanite displays specific color characteristics and clarity that can help distinguish it from fake or synthetic stones.

• Color: Genuine tanzanite typically exhibits a vibrant blue to violet hue. High-quality stones may show a rich, saturated blue with violet undertones, while lower-quality pieces might appear dull or washed out. The color should be evenly distributed without streaks or patches.
• Color Change: Tanzanite is known for its pleochroism—meaning it can show different colors when viewed from different angles. Under certain lighting, it may appear more blue, violet, or purple. This optical property is characteristic of real tanzanite.
• Clarity: While some inclusions are natural and common, especially in lower-grade stones, overly cloudy or eye-visible inclusions may indicate a fake or treated stone. Authentic tanzanite often has some inclusions but maintains a generally clear appearance.
• Surface Quality: Check for surface blemishes or scratches. A genuine, well-cut tanzanite will have a smooth, polished surface without chips or cracks.

Testing Optical Properties and Light Behavior

Since tanzanite’s optical properties are distinctive, observing how the stone interacts with light can be revealing.

• Pleochroism: As mentioned earlier, real tanzanite displays strong pleochroism. Hold the gemstone and rotate it under a light source. You should notice a shift in color from blue to violet or purple. If the stone remains uniformly colored or lacks this effect, it could be synthetic or fake.
• Color Intensity Under Different Lights: Genuine tanzanite looks vibrant under natural daylight but may appear dull or different in artificial lighting. Examine the stone in various lighting conditions to assess its true color.
• Fire and Brilliance: Tanzanite tends to have a moderate brilliance but not the high sparkle of diamonds or sapphires. If the stone appears overly sparkly or glassy, it might be a synthetic or imitation.

Hardness and Physical Tests

Physical tests based on the gemstone’s hardness and durability can help identify real tanzanite. As a relatively soft gemstone, tanzanite can be distinguished from harder stones.

• Hardness Test: Tanzanite ranks 6.5 to 7 on the Mohs scale. You can perform a scratch test using a material of known higher hardness (like a quartz or a steel blade), but caution is advised to avoid damaging the stone. Typically, tanzanite can be scratched by materials harder than 7, such as sapphires and diamonds.
• Temperature Test: Genuine tanzanite feels cool to the touch and warms up slowly. However, this is a less reliable method and should be performed carefully.

Refractive Index and Specific Gravity

Advanced testing methods can provide more definitive proof of authenticity.

• Refractive Index (RI): The RI of tanzanite ranges from approximately 1.69 to 1.70. A gemologist can measure this using a refractometer. Fake stones often have different RI values, making this a reliable test.
• Specific Gravity: The specific gravity of genuine tanzanite is around 3.35. This can be tested with specialized equipment. Deviations from this value might indicate a fake or treated stone.

Testing for Treatments and Enhancements

Many tanzanites on the market are heat-treated to enhance their color. While heat treatment is widely accepted in the industry, it’s essential to know whether a stone has been treated and if so, to what extent.

• Color Zoning: Treated tanzanite often displays uniform color, whereas natural stones may have zoning or slight variations.
• Inclusions: Heating can sometimes change the appearance of inclusions. Under a microscope, natural inclusions like needles or mineral crystals may persist, indicating a natural stone.
• Professional Appraisal: The best way to confirm whether a tanzanite has been treated is through a professional gemological report from a reputable laboratory.

Buying from Reputable Sources and Certificated Stones

One of the most reliable ways to ensure you’re purchasing a genuine tanzanite is to buy from trusted dealers and request certification from recognized gemological laboratories such as GIA or IGI. Certified stones include detailed reports verifying authenticity, treatment history, and quality grade.

• Always ask for certification when purchasing high-value gemstones.
• Buy from reputable jewelers with positive reviews and transparent sourcing policies.
• Be cautious of prices that seem too good to be true, as they often are.

Summary: Key Points to Confirm Authentic Tanzanite

To determine if a tanzanite is real, consider the following key points:

• Examine the color—vibrant blue-violet hues with pleochroism are characteristic of genuine tanzanite.
• Look for natural inclusions and surface quality—overly perfect stones may be synthetic or fake.
• Perform optical tests, such as observing pleochroism and color change under different lighting conditions.
• Use physical tests cautiously; check hardness and consider professional testing for RI and specific gravity.
• Request certification from reputable laboratories to verify authenticity and treatment history.
• Purchase from trusted sources to minimize the risk of buying fake or treated stones.

By combining these visual, physical, and professional evaluation methods, you can confidently identify genuine tanzanite and enjoy this rare, beautiful gemstone with peace of mind. Remember, when in doubt, consulting a gemologist is always a wise choice to ensure your investment is authentic and valuable.