Alexandrite, a technical guide on June’s birthstone.

Introduction

Alexandrite is a rare chrysoberyl variety valued for its distinct color change properties. Its color change properties symbolize adaptability and balance, making it an appealing choice for individuals born in June. This Alexandrite guide you on walk you on its technical properties.

Alexandrite color change mechanism

The color change effect in Alexandrite arises from chromium elements in its chemical structure and under daylight, Alexandrite appears greenish, whilst under incandescent light it shifts to red or purplish red.  Different geographical origins also present different changes.

• Russia (Ural Mountains): Exhibits a green to red color change with strong saturation.

• Sri Lanka: Typically shows a lighter green to brownish / orangish red change.

• Brazil: Displays bluish green to purplish red changes.

• Tanzania & Madagascar: Often moderate to strong color change, sometimes with brownish undertones.

Guide on value factors in Alexandrite

1. Color Change Quality

   The most significant factor. A strong and distinct green to red color change commands higher prices.

2. Saturation and Hue

   Stones with intense green and red hues are more desirable whilst brownish or greyish secondary reduce value.

3. Clarity

   Alexandrite often contains inclusions and eye-clean stones are rarer and more valuable.

4. Carat Weight

   Larger Alexandrites are rare and stones above 1 carat with good color change are especially valuable.

5. Cut

   Well-cut stones maximize the color-change effect and brightness.

6. Origin

   Russia (Ural Mountains) are historically the most valued, especially those with a vivid green to red change.

   Brazil and Tanzania can be valuable, particularly if they exhibit a strong and vibrant color change like the Russian.

   Sri Lanka tend to be more affordable, as their color change is often less pronounced.

Identifying natural vs. synthetic Alexandrite

Often it can be identified with the use of a microscope, by checking its inclusions and growth patterns, as natural stones will show angular growth lines and natural mineral inclusions, whilst synthetic ones will show curved growth lines with flux residue, or gas bubbles.

Advanced testing by an independent gemological laboratory, with UV-Vis-NIR spectroscopy, X-ray diffraction, and trace element profiling can be used for conclusive identification.

Conclusion

Alexandrite’s unique optical properties and rarity are important factors to its status as one of the more valuable colored gemstones in the market. And at TWAK we can find the perfect Alexandrite for you and turn it into a bespoke jewelry piece with our Gem to Jewelry program.