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

What is pearl?

Pearls are organic gems of nacre grown by molluscs; nearly all on the market are cultured. Hardness: 2.5–4.5 on the Mohs scale.

Colour and quality factors

Lustre and surface quality matter most, then shape, size, colour and nacre thickness. Matching is key in strands.

Origins and natural (mined) stones

Japan/China (Akoya), Australia, Indonesia and the Philippines (South Sea), French Polynesia (Tahitian), China (freshwater). Natural pearls come mainly from the Persian Gulf historically.

Carat weight and size

Pearls are measured in millimetres (and natural pearls in grains), not carats. Each extra millimetre raises price significantly.

Prices per carat

Freshwater strands: roughly $100–$2,000. Akoya: $500–$5,000. Tahitian and South Sea: $1,000–$25,000+. Natural pearls: auction prices often far 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)

There are no 'lab-grown' pearls; cultured pearls are grown in molluscs with human help. Imitation pearls (glass or plastic) must be labelled. 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

Bleaching, dyeing and polishing are common; dyed colours must be disclosed. Treatment disclosure is required; ask for it in writing and on the lab report.

Certification

For significant pearl 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

Last on, first off: avoid perfume, ultrasonic cleaners and storage with hard gems; restring periodically.

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