Alexandrite Buying Guide: Colour Change, Rarity & Price

Alexandrite is defined entirely by one extraordinary property: a genuine shift in colour depending on the light it's viewed under, caused by trace chromium in its chrysoberyl crystal structure.

The colour-change effect

In daylight, rich in blue and green wavelengths, alexandrite reads green; under incandescent light, rich in red wavelengths, the same stone reads red. The chromium responsible absorbs light specifically in the yellow part of the spectrum, which is what makes the shift possible at all. The most valuable stones show a vivid, high-contrast change between the two colours — a weak or muddy shift is worth dramatically less than a strong, clean one, even at identical carat weight and clarity.

Genuinely, extremely rare

A natural, eye-clean alexandrite with a strong colour change is rarer than a large flawless diamond — the specific geological conditions needed to form it are an anomaly even by fine-gemstone standards. This scarcity, not marketing, is what drives alexandrite's price into territory that surprises buyers unfamiliar with the stone: fine natural material starts in the thousands of dollars per carat and climbs sharply from there for larger, more saturated, stronger-shifting stones.

Lab-grown alexandrite: a legitimate, much cheaper alternative

Lab-grown alexandrite shares the same chemical composition and displays a genuine colour-change effect, typically at a small fraction of natural pricing. It's a legitimate way to own real colour-change chrysoberyl without the extreme cost of natural material — but it carries none of natural alexandrite's rarity or resale value, the same trade-off as lab-grown vs natural diamond. Always confirm which you're buying; the two look identical without disclosure.

What to check before buying

• Strength and cleanliness of the colour change, viewed under both daylight and incandescent light if at all possible — photos alone are unreliable for this specific stone.
• Natural vs lab-grown, confirmed on an independent report — never assumed from appearance alone.
• Origin, where determinable — Russian, Brazilian and Sri Lankan material each carry different rarity and price expectations, and a specialist dealer can advise which is realistic at your budget.

Related reading

• Non-diamond engagement rings: sapphire, ruby, emerald & moissanite
• Do lab-grown diamonds hold their value?
• Alexandrite guide

Sources: colour-change mechanism and rarity per GIA (gia.edu) and specialist trade retailer pricing commentary (Brilliant Earth, AfricaGems).