Known for their striking beauty and rarity, alexandrite and other chrysoberyl varieties are some of the most fascinating gemstones in the world. Best known for alexandrite’s dramatic colour change and chrysoberyl’s chatoyancy (cat’s eye effect), these gems are prized for their brilliance, durability, and optical phenomena.
What is Alexandrite?
Alexandrite is a rare variety of the mineral chrysoberyl, first discovered in the Ural Mountains of Russia in the 1830s. It’s renowned for its remarkable colour change—from green in daylight to red or purplish-red under incandescent light. This optical property, known as pleochroism, makes alexandrite one of the most desirable and valuable gemstones in the world.
What is Chrysoberyl?
Chrysoberyl refers to the mineral family that includes alexandrite and cat’s eye chrysoberyl. While not as rare as alexandrite, other chrysoberyl gemstones are equally admired for their durability and vibrant yellow to green hues. The cat’s eye variety displays a bright, reflective line across the stone’s surface due to fine inclusions—an effect known as chatoyancy.
Gemstone Characteristics
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Hardness: 8.5 on the Mohs scale
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Toughness: Excellent
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Lustre: Vitreous
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Crystal System: Orthorhombic
- Colour: Alexandrite – green to red; Chrysoberyl – yellow to green
Common Cutting Styles
Alexandrites are most often cut as ovals or cushion shapes to maximise their colour change. Cat’s eye chrysoberyls are typically cut as cabochons, enhancing the visual impact of the chatoyancy. Faceted chrysoberyl may be cut in traditional step or mixed cuts to show off its clarity and brightness.
Use in Jewellery
Though extremely rare in antique pieces due to their scarcity, alexandrites occasionally appear in high-value Victorian and Edwardian rings. Cat’s eye chrysoberyl was more frequently used in the late 19th and early 20th centuries, particularly in men’s rings and Eastern-inspired designs. These gemstones are ideal for everyday wear due to their excellent hardness and toughness.
Historical Significance
Alexandrite was named in honour of Tsar Alexander II and quickly became associated with the Russian aristocracy. Because of its red and green hues—colours of Imperial Russia—it gained patriotic significance. The cat’s eye variety, meanwhile, has long been a symbol of protection in many cultures and is especially popular in Indian jewellery traditions.