Alexandrite Buying Guide: Natural vs Lab-Grown, Prices per Carat & Quality

What is alexandrite?

Alexandrite is a colour-change variety of chrysoberyl. Hardness: 8.5 on the Mohs scale.

Colour and quality factors

The strength of the colour change is everything: a clear bluish-green to purplish-red shift is ideal. Weak or brownish change lowers value.

Origins and natural (mined) stones

Russia's Urals (historic), Brazil, Sri Lanka, India and East Africa.

Carat weight and size

Most natural alexandrites are under 1 ct; fine stones over 2 ct are rare and priced exponentially higher.

Prices per carat

Weak-change commercial: roughly $500–$3,000/ct. Good change 1 ct: roughly $8,000–$20,000/ct. Exceptional larger stones: $30,000–$70,000+/ct. These are indicative retail ranges per carat gathered from published trade and auction reporting; real prices vary widely with colour, size, origin and treatment, and are not a Riakoob quote.

Natural vs lab-grown (synthetic)

Lab alexandrite (flux, Czochralski) shows strong colour change and typically costs about $50–$1,500/ct. Much 'alexandrite' sold cheaply is actually synthetic colour-change sapphire or spinel — a simulant. Under US FTC guidelines a lab-made stone must be clearly described as laboratory-grown, laboratory-created or synthetic, never simply by the gem name.

Treatments you must know about

Natural alexandrite is usually untreated; occasional oiling of fractures. Treatment disclosure is required; ask for it in writing and on the lab report.

Certification

For significant alexandrite purchases, ask for a report from an independent lab such as GIA, AGL, SSEF or Gübelin stating natural or synthetic origin, any treatments and, where relevant, geographic origin.

Care and durability

Hard and tough — very suitable for rings.

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