Material Identity
Alexandrite is a chromium-bearing variety of chrysoberyl, BeAl2O4, with a Mohs hardness of 8.5. The names chrysoberyl and beryl sound close, but they are different minerals: emerald, aquamarine, and morganite are beryls, while alexandrite is not. The chromium in its structure is what allows the gem to register green in one light and red in another. Other materials can change color too, yet the name alexandrite belongs to this chrysoberyl alone; a color-change sapphire or garnet is not alexandrite, whatever the display lighting suggests.
Visual Character
Everything about this gem turns on the change itself. In daylight or fluorescent light a fine alexandrite reads green to bluish green; move it beside an incandescent bulb and it swings toward red, purplish red, or amethystine tones. Value follows the drama of that swing: the most admired stones travel from bluish green to red or purplish red with moderately strong to strong saturation, while a partial shift or a grayish middle tone softens the effect and the price. A photograph cannot carry this information, because every image is taken in one light. Any honest account of an alexandrite names which color appears under which source.
Meaning and Cultural Context
The gem surfaced in 1830 in Russia's Ural Mountains, reportedly near the region's emerald mines, and was named for Czar Alexander II. That origin gave it an enduring air of ceremony, rarity, and doubled identity, green by day and red by night, a pairing often linked in Russian tradition to the imperial colors themselves. Wearers frequently read the stone as an emblem of balance between two states, a meaning sustained as cultural memory and personal significance.
Jewelry and Care
Alexandrite ranks 8.5 on the Mohs scale and has no problematic cleavage, so it handles ring wear and daily jewelry with confidence. Warm water, mild soap, and a soft brush keep it bright; as with any fine gem, a hard knock against a countertop can still chip an edge, so settings that shelter exposed points are worthwhile.
Choosing This Stone
Let the change lead. View the stone in daylight or fluorescent light, then under incandescent light, and note how complete and saturated the green-to-red passage is; strength of change outweighs size for most collectors. Keep the naming precise: Zultanite and other color-change gems belong to the same conversation but not to the same material, and each carries its own identity into a piece of jewelry.