Gemstone Treatments: What Jewelers Must Disclose

Heat treatment: Applied to 95% of rubies and sapphires on the market. Heats stones to 1,600-1,800 degrees C to improve color and clarity. Generally stable and permanent.

Fracture filling: Glass or resin injected into surface-reaching cracks, primarily in rubies. Not permanent - can be damaged by heat or chemicals. Oiling: Emeralds are almost always oiled with cedar oil to reduce visibility of fractures.

Irradiation: Used to create blue topaz and some colored diamonds. Must be tested for residual radioactivity. Dyeing: Applied to howlite (fake turquoise), cracked quartz, and onyx. Always ask about treatments before purchasing. Federal Trade Commission requires disclosure..