How to Buy a Genuine Alexandrite

Fine alexandrite is prized specifically because it reaches the market untreated — there's no accepted heat-treatment or enhancement convention for this gem the way there is for ruby or sapphire, so a certificate's main job is confirming genuine natural chrysoberyl rather than reporting a treatment. The real risk in this market is substitution: color-change synthetic corundum and color-change synthetic garnet are both manufactured specifically to imitate alexandrite's effect and are routinely sold to buyers who don't request species verification.

The strength of the color change is the dominant value driver, full stop — a dramatic, complete shift from vivid green to vivid red is exceptionally rare and commands prices among the highest of any colored stone per carat, while a weak or partial shift is worth considerably less even in a stone of identical size. Color vividness in each individual lighting condition matters next, followed by clarity and carat weight — genuine alexandrite over 1 carat with a strong, complete color change is rare enough that size alone drives a steep price premium once you're past that threshold.

Because synthetic color-change corundum and garnet imitate the effect convincingly to the naked eye, don't rely on the color change alone as proof of authenticity — insist on an independent certificate confirming genuine chrysoberyl. When comparing stones, view them under both daylight (or a daylight-equivalent lamp) and warm incandescent light before buying, since a seller's photos or a single lighting condition can make a weak color-change stone look more dramatic than it really is.

For certification specifics, see our Alexandrite certification guide, or check current Alexandrite prices. General authenticity standards that apply across every gemstone we handle are covered on the site-wide Authenticity & Certification page.