Gemstones
Amethyst Buying Guide: Natural vs Lab-Grown, Prices per Carat & Quality
Siberian-colour amethyst, Uruguay and Zambia origins, synthetic quartz, carat sizes and amethyst prices.
What is amethyst?
Amethyst is purple quartz coloured by iron and natural irradiation. Hardness: 7 on the Mohs scale.
Colour and quality factors
Deep purple with red-violet flashes ('Deep Siberian' trade grade) is most valued; pale 'Rose de France' is affordable.
Origins and natural (mined) stones
Brazil, Uruguay, Zambia, Bolivia (ametrine) and Russia historically.
Carat weight and size
Plentiful in large sizes, so price per carat stays modest even for big stones.
Prices per carat
Commercial: roughly $2–$20/ct. Fine deep colour: roughly $20–$60/ct. Exceptional: higher. 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)
Hydrothermal synthetic amethyst is widely produced and inexpensive; separation can require advanced testing. 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
Heat can lighten colour or turn amethyst into citrine; disclose when known. Treatment disclosure is required; ask for it in writing and on the lab report.
Certification
For significant amethyst 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
Durable; colour can fade with prolonged strong sunlight.
Buyer checklist
- ✓ Even saturated colour
- ✓ Natural vs synthetic for important stones
- ✓ Avoid long sun exposure
Verification tools & references
Every Riakoob piece arrives certified, insured and covered by our 12-month value promise.
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