Alexandrite, with its mesmerizing color-changing properties, is a highly sought-after gemstone. However, its rarity and desirability make it a prime target for counterfeiting. Knowing how to authenticate alexandrite is crucial for both buyers and collectors. This guide will equip you with the knowledge to distinguish genuine alexandrite from its imitations.
What Makes Alexandrite Unique?
Before delving into identification methods, understanding alexandrite's unique characteristics is vital. Genuine alexandrite exhibits a remarkable color-change effect, appearing different hues under various lighting conditions. This phenomenon, known as alexandrite effect, is its defining characteristic. Typically, it displays emerald green in daylight and red or purplish-red under incandescent light. The intensity of the color change varies depending on the stone's quality and origin.
How to Identify Real Alexandrite: Key Tests and Observations
Several methods can help determine the authenticity of alexandrite:
1. The Color-Change Test: The Hallmark of Authenticity
This is the most crucial test. Observe the alexandrite under different light sources. Does it exhibit a distinct and significant color shift, as described above? A subtle shift or lack of color change is a strong indicator of a fake. Compare it under natural daylight (or a daylight-balanced lamp) and incandescent lighting (a warmer-toned light). The contrast should be noticeable.
2. Examine the Clarity and Inclusions:
Real alexandrites, like most natural gemstones, usually have inclusions – natural internal flaws. These inclusions are unique and can be used to help identify the stone. While flawless alexandrites exist, they are extremely rare. Examine the stone closely under magnification. The presence of natural-looking inclusions points towards authenticity. Artificial stones often lack these natural imperfections.
3. Check for Fluorescence Under UV Light:
Many alexandrites exhibit fluorescence under ultraviolet (UV) light. However, the intensity and color of fluorescence can vary. While this test isn't definitive on its own, a lack of fluorescence under UV light can raise suspicion. It is important to note that this is not a definitive test for authenticity. Some real alexandrites may not fluoresce, while some synthetic ones might.
4. Assess the Cut and Polish:
High-quality alexandrites usually have excellent cuts and polish. Poorly cut or polished stones might suggest a lower quality or a counterfeit. Look for smooth, even facets and a high level of brilliance.
5. Check the Refractive Index:
This test requires specialized equipment. A gemologist uses a refractometer to measure the refractive index of the stone. Alexandrite has a refractive index range of 1.744-1.755. This provides a more scientific confirmation of authenticity.
6. Spectroscopic Analysis:
This is another advanced test performed by gemologists using a spectroscope. The spectroscope reveals the absorption spectrum of the stone, providing unique characteristics that can be compared to known alexandrite spectra.
What to Watch Out For: Common Alexandrite Imitations
Several materials are used to imitate alexandrite:
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Synthetic Alexandrite: Lab-grown alexandrite is chemically identical to natural alexandrite, but it lacks the inherent value and history. Sophisticated testing is often necessary to differentiate between natural and synthetic alexandrite.
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Glass: Glass imitations are often inexpensive and easily distinguishable by their lack of color change and the absence of inclusions.
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Spinel and Garnet: Some spinel and garnet varieties can have a similar color, but usually lack the distinct color-change effect of alexandrite.
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Other Treated Gemstones: Some other gemstones might be treated to mimic alexandrite's color, but careful observation and testing will usually reveal differences.
Where to Buy Authentic Alexandrite?
Purchasing alexandrite from reputable jewelers or gem dealers is crucial. Reputable sellers often provide certificates of authenticity from qualified gemological laboratories, confirming the stone's natural origin and quality.
Frequently Asked Questions (FAQs):
How much is a real alexandrite worth?
The value of alexandrite depends on many factors, including size, color intensity, color change, clarity, and cut. High-quality alexandrite can be quite expensive, making it a valuable investment.
Can I test alexandrite authenticity at home?
While some basic tests like the color-change test and observation of inclusions can be performed at home, more sophisticated tests like refractive index measurement and spectroscopic analysis require specialized equipment and expertise.
How rare is alexandrite?
Alexandrite is considered a very rare gemstone, far rarer than diamonds, rubies, or emeralds. Its rarity contributes significantly to its high value.
What are the ethical considerations when buying alexandrite?
Ensuring the alexandrite is ethically sourced, meaning it was mined and traded responsibly and sustainably, is essential. Look for sellers who promote ethical and responsible practices.
By carefully examining the stone and understanding its unique characteristics, you can significantly increase your chances of identifying authentic alexandrite and avoiding imitations. Remember that when in doubt, consulting a qualified gemologist is always the best course of action.
