Not necessarily. Heat treatment is widely accepted and permanent. The key is disclosure - reputable dealers must tell you about any treatments. Untreated stones are most valuable, but treated stones offer good value if properly disclosed.

Heat treatment uses high temperatures to improve color and clarity. It's permanent, widely accepted, and used on sapphires, rubies, and other stones. Heat-treated stones are worth 70-90% of untreated equivalents.

Ask the seller directly - they must disclose treatments. Check certification from recognized labs (GIA, AGS). Some treatments are visible under magnification. Buy from reputable dealers who guarantee disclosure.

Permanent treatments (heat, irradiation) last forever. Temporary treatments (fracture filling, coating) can wear off over time and require special care. Always ask if treatment is permanent.

We clearly disclose all treatments. Our Queensland sapphires are 100% natural and untreated. When we sell treated stones (like blue topaz), we always state the treatment type. Browse our untreated gemstones.