Alexandrite is the gemstone designated for the 55th wedding anniversary, a milestone so uncommon that fewer than five per cent of married couples reach it. The choice is apt: alexandrite is among the rarest and most scientifically remarkable gemstones in the world, prized above all for its dramatic colour-change — shifting from bluish or yellowish green in daylight to purplish or brownish red under incandescent light. That capacity for transformation, sustained across a single stone, has long made alexandrite a natural symbol of adaptability and enduring wonder — qualities that mirror a marriage of more than half a century.

The Designation and Its Alternatives

The 55th anniversary gemstone assignment is recognised by Jewelers of America, the principal trade body that maintains the modern standardised list of anniversary stones in the United States. Emerald is occasionally cited as an alternative for this milestone, particularly in older or regionally variant lists, though alexandrite has become the more widely accepted modern designation. The 55th anniversary sits outside the heavily commercialised tier of major milestones — 25th (silver), 50th (gold), 60th (diamond) — and consequently the alexandrite association is less universally known, though no less meaningful for those who reach it.

Alexandrite: The Gemstone

Alexandrite is a chromium-bearing variety of the mineral chrysoberyl (BeAl₂O₄), with a hardness of 8.5 on the Mohs scale and excellent toughness. Its colour-change arises because chromium absorbs light in such a way that the stone transmits both green and red wavelengths; which predominates depends on the spectral composition of the illuminating light source. Fine natural alexandrite showing a strong, clean colour-change — ideally a vivid green to a rich red — commands prices comparable to fine ruby or emerald, and exceptional stones from the original Russian deposits in the Ural Mountains remain among the most coveted collector gems in existence.

Modern supply comes principally from Brazil (state of Minas Gerais), Sri Lanka, and East Africa (Tanzania and Madagascar), with smaller quantities from India and Myanmar. Russian alexandrite, mined from the Tokovaya River deposits discovered in the 1830s, is historically the benchmark: its colour-change tends toward a more saturated green and a more distinctly red secondary hue than material from most other localities. Sri Lankan stones are often larger but may show a less dramatic shift, while Brazilian alexandrite can rival Russian material in colour-change intensity.

Treatments and Synthetic Material

Natural alexandrite is generally not treated — heat treatment and fracture filling are not standard practice for this species, and the gem is typically sold as found. However, buyers should be aware that synthetic alexandrite, produced by the flux and Czochralski (pulling) methods, is widely available and visually convincing. Synthetic material shows a strong colour-change and is chemically identical to natural alexandrite, but lacks the inclusions and growth features of natural stones. Laboratory identification by a recognised gemmological laboratory — GIA, Gübelin, or SSEF — is strongly recommended for any significant purchase, particularly for stones presented as natural Russian or Brazilian alexandrite.

Selecting a 55th Anniversary Gift

Given alexandrite's rarity, a fine natural stone in even a modest size (0.50–1.00 carat) represents a genuinely significant gift. Key quality factors to consider include:

• Colour-change strength: the more complete and vivid the shift between green and red, the more valuable the stone.
• Colour quality in both lights: ideally a clean, saturated green in daylight and a warm, distinct red under incandescent light, without brownish or greyish masking tones.
• Clarity: eye-clean stones are preferred; alexandrite commonly contains silk, fingerprint inclusions, and growth tubes, but heavy inclusions reduce value.
• Origin documentation: a laboratory report confirming natural origin and, where determinable, geographic origin adds both confidence and long-term value.

Those for whom the cost of fine natural alexandrite is prohibitive may consider a well-cut synthetic stone set in a meaningful mounting, or a fine emerald as the traditional alternative — both remain entirely appropriate tributes to a 55-year marriage.