How to Identify Alexandrite Stone

Have you ever come across a beautiful purple-red gemstone that seems to shift to green? You may be fortunate enough to have stumbled upon rare and valuable Alexandrite! But how can you be sure it’s the real deal?

Identifying genuine Alexandrite requires detecting the dramatic color change this stone is prized for, while ruling out look-alike imposters. Arm yourself with the facts and tests covered in this guide, and you’ll be on your way to unveiling Alexandrite’s treasures.

The Illusive Chameleon of Gems

Alexandrite dazzles – there’s no denying it. When you first glimpse the soft, bluish-green hues, you’ll do a double take as it transforms to a raspberry red. This impressive colour change makes Alexandrite one of the most desirable gemstones.

So why the head-scratching identity crisis? This phenomenal effect stems from Alexandrite’s chemical composition. It’s the colour change variety of the mineral Chrysoberyl, containing trace amounts of chromium. This gives it a unique molecular structure that absorbs different wavelengths of light. Bluish-green in daylight, and purplish-red under incandescent light.

You’ll rarely come across such vivid colour changes in other gems. This distinctive trait makes answering “Is this Alexandrite?” easier, provided you know what signs to search for.

In this guide, you’ll gain an Alexandrite education with tips for spotting authentic specimens. I’ll walk you through:

  • Alexandrite’s trademark properties that aid identification.
  • Tests to be conducted on suspect stones.
  • When it’s vital to get a professional second opinion.
  • How to shield yourself from tricky synthetics and treatments.

Let’s get started unmasking Alexandrite in its many disguises!

What Makes Alexandrite One-of-a-Kind?

Before identifying an Alexandrite contender, it helps to understand what qualities make this stone so exceptional. Here are the signature traits that set it apart as a colour-change heavyweight:

Dramatic Color Change: Chameleon of Gems

Alexandrite dazzles and delights with its color-shifting prowess. In daylight, it appears as an appealing bluish mossy green. But view it under incandescent or candlelight, and it morphs to a raspberry or purple-red.

This rare colour change ability results from the trace amounts of chromium in Alexandrite’s chemical makeup. The chromium acts as a colouring agent, displaying green in daylight and red under different lighting conditions.

Other gems also exhibit colour change, like rare Sapphires and Garnets. But their effects tend to be much subtler, with barely perceptible shifts. Alexandrite stands out for its dramatic, distinctive metamorphosis.

The most valuable Alexandrites show a vivid and pronounced transition between green and red hues. The stronger the change, the higher the quality of the gem. Weak colour change usually signifies an imposter.

Intensely Saturated Hues

Alexandrite captivates with its rich, intense colours in both light spectrums. Vivid emerald greens and deep, raspberry reds are the most prized.

The look-alike gems that display colour change often appear washed out or brownish. Their hues lack the vivid saturation of fine Alexandrites.

Examine colour concentration in all lighting conditions. Paler shades likely indicate a fake.

Hardness and Durability

On the Mohs scale of mineral hardness, Alexandrite ranks a very respectable 8.5 out of 10. For comparison, Diamonds register the maximum 10 rating, while Quartz measures 7. This hardness makes Alexandrite a durable stone suited to jewellery use.

Try to scratch the surface of a sample stone with a steel nail file or knife blade. Authentic Alexandrites will remain unscathed.

Distinctive Inclusions

Like all natural gems, most Alexandrites contain tiny mineral deposits called inclusions. These birthmarks arise as the stone forms over millions of years.

Under magnification, a distinctive “Cat’s Eye” needle-like inclusion pattern emerges in many Alexandrites. The gem also displays a doubling of facets, due to its high refractive qualities. Compare the inclusions in a test stone against standard Alexandrite patterns to aid identification.

Few imitations accurately mimic these characteristic internal features.

Evaluating for the Alexandrite Effect: Magical Color Change

The phenomenal colour changeability makes or breaks an Alexandrite. Let’s explore techniques for assessing this telltale identifying trait:

View in Multiple Light Sources

Find two different light sources – daylight and incandescent light bulbs work perfectly. Position the stone under the daylight bulb first. Rotate and tilt the gem, looking for any tinge of green or blue. Then scrutinize under the incandescent bulb for hints of purple-red.

The most pronounced, vivid change between blue-green and raspberry red signals a potential Alexandrite. Subtle, muddy shifts likely mean the stone lacks true Alexandrite’s color-changing powers.

Ideally, also evaluate in natural light conditions. Direct sunlight followed by candlelight approximates Alexandrite’s changes best.

Judge Color Concentration

Does the stone display rich, intense hues in both lighting setups? Or do the colours seem weak and diluted?

True Alexandrites exhibit vivid emerald greens and saturated raspberry reds. Washy, pale shades are telltale signs of an imposter.

What Color Combos Occur?

While red to green dazzles most, Alexandrites can also transition between other colour combinations. Blue to purple, green to brownish-orange, green to red-purple also occur.

Not all Alexandrites will have the perfect crisp green-to-red change. Judge each stone individually for the colour intensity present.

No Change Means Failure!

If the stone shows no perceptible colour change under different lighting, it cannot be Alexandrite. The chameleon effect is the number one giveaway.

Treat any claims that a non-changing stone is Alexandrite with extreme scepticism. Demand proof if sellers insist it’s the real deal.

Beware Weak Change

Some shady dealers try to pass off poor-quality colour change gems as Alexandrite. Know that dramatic change signals value. Weak transitions to slightly different hues have little worth.

Always scrutinize for vivid, bold colour shifts when identifying Alexandrite specimens. subpar chameleons need not apply!

Checking for Inclusions: Clues Under the Surface

Think of gemstone inclusions as fingerprint evidence. These microscopic imperfections often form in distinctive ways as a stone grows over aeons.

For Alexandrite, check that:

  • Characteristic cat’s eye needles and doubling effect are present.
  • Inclusions don’t affect colour change or clarity severely.

Here’s how to detect these revealing features:

Examine Under Magnification

Use a loupe, microscope, or jeweller’s magnification to inspect the interior. Search for creamy cat’s eye lines, small crystals, and doubling of facets.

Compare against an inclusions guide to spot patterns unique to natural Alexandrite.

Mark of High Quality

Better Alexandrites have fewer, smaller inclusions that don’t detract from colour or transparency. Numerous heavy inclusions likely mean lower quality. But some inclusions should be present to confirm natural origins.

Watch for Imitation Inclusions

Beware imitations with fake “seeding.” Check any suspicious dots or clouds under high magnification to judge if they are natural or artificial.

Double Refraction Shows Through

You can observe Alexandrite’s high refractive qualities by focusing on the stone’s facet junctions. Mismatched doubling indicates true Alexandrite, not seen in synthetics.

Meticulous inspection of interior hallmarks can help avoid being hoodwinked. Now let’s move on to testing the stone’s hardness…

Rating Hardness: Built to Last

Hardness relates to a mineral’s durability and toughness. We measure this using the Mohs scale, with diamonds scoring a perfect 10.

With a rating of 8.5, Alexandrite ranks among the harder gems. This high resistance to scratching helps confirm authenticity.

Here’s how to assess hardness:

Mohs Test Kit

A simple hardness testing kit scratches stones against materials of known hardness. Sapphire at 9 and Topaz at 8 should scratch Alexandrite. In turn, Alexandrite will scratch Quartz at 7.

Scratching the sample with steel cutlery can also give an estimate. Alexandrite will remain unmarked.

Tough Yet Brittle

Mind that Alexandrite can be brittle if knocked sharply, though overall hard. Check for any chips and cracks that may indicate brittleness or prior damage.

Imposter’s Soft Spot

Many fake colour-change gems like Glass and Synthetic Spinel have much lower hardness around 5-7. They’ll show scratches from Quartz, steel objects, and fingernails. A soft stone is a red flag.

Evaluating hardness takes just essential tools and keen observations. Now let’s move on to the experts’ arsenal for confirmation…

When To Call In The Pros: Advanced Testing

So far we’ve stuck to basic tests doable at home or with a jeweler’s help. But for final proof, consider calling in the big guns.

Professional gem labs have a cutting-edge tech to analyze and certify Alexandrites. Here are the key advanced identification tests:

Spectroscopic Analysis

Sophisticated spectrometers can pinpoint the exact chemical composition. They detect the chromium trace that causes Alexandrite’s distinctive colour change. Labs can also spot any treatments.


Powerful gemological microscopes magnify inclusions, confirming they match natural Alexandrite. Experts also examine for any suspicious repair cavities, fractures, or unnatural clouds.

Advanced Refractive Tests

Special refractive index liquid measurements take precise readings of how much incoming light is bent. The readings must fall within Alexandrite’s established range.

Gemologist Wisdom

A trained professional gemologist combines scientific testing with years of experience. They may spot subtle warning signs of synthetic origins or treatments. Trust an expert’s learned instincts.

These high-tech tests give conclusive proof of authenticity. They also establish any presence of treatments. Pros provide the safest route for pricier specimens.

Guarding Against Fakes and Treatments

So you’ve fallen for Alexandrite and want some of your own. Be vigilant against the flood of synthetics and imposters out there:

Synthetic Alexandrite

Alexandrite synthesis became possible in the late 19th century. Russian labs still produce it commercially, along with other sources. Ensure any synthetic is disclosed at sale.

Although chemically identical, synthetic Alexandrite often shows perfect clarity and color unnatural in nature. Inclusions will also differ. Advanced testing can identify lab origins.

Simulant Stones

Numerous gem varieties attempt to mimic Alexandrite, from Sapphire to Spinel to Glass. But none truly re-create that incredible colour change.

Apply the identification tips to weed out pretenders. Beware uncertified stones with unbelievable price tags.

Treatment Dangers

Some dealers enhance Alexandrite artificially to intensify colour. This underhanded practice leaves the stone more fragile.

Request proof no treatments were used. Leave any suspected specimens to the pros for evaluation.

Stay vigilant for dishonest dealers who fail to disclose treatments or synthetic origins. Work only with trusted, certified vendors, and you’ll avoid being swindled.

Unleash Your Inner Alexandrite Expert!

We’ve covered a lot of ground on revealing Alexandrite in disguise. Here are the key identification takeaways:

  • Seek out dramatic colour shifts from bluish-green to red/purple under varying light. Vivid, saturated hues signal prime quality.
  • Use magnification to search for distinctive cat’s eye inclusions. Double refraction adds proof of authenticity.
  • Hardness tests should show resistance to scratching from knives, Quartz and below. Alexandrite ranks 8.5 on Mohs scale.
  • For final confirmation and accurate valuation, consult a professional gemological lab. Advanced testing establishes if natural and untreated.
  • Watch for synthetics, imitations and dishonest enhancements. Work only with trusted sellers providing certification.

Now get out there and unleash your newfound Alexandrite identification powers! With this knowledge, you have what it takes to distinguish the genuine gems from their many imposters.

Do you have any other tips for identifying true Alexandrite? Any favourite colour-change stones? Share your experiences finding these coveted chameleons!

Jyotish Varsha Gupta
Varsha Gupta


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