Irradiation is exposing a gem to artificial radiation to change its color. Heating sometimes follows, to modify the color further.
In more detail
Some irradiated colors fade in strong light. Irradiated yellow sapphire, for example, fades fast when held near a flame. An irradiated stone cannot be called padparadscha.
On a grading report
Labs state the treatment when they detect it.
Related terms
- Treatment: A treatment is any process, other than cutting and polishing, that changes a gem's color or apparent clarity. Anyone who sells a treated gem must disclose the treatment.
- Stability: Stability is a gem's resistance to damage from heat, light and chemicals.
- Padparadscha: Padparadscha is a sapphire of soft pinkish orange to orangey pink. Its tones are pastel and its saturation low to medium.
- Disclosure: Disclosure is telling the buyer, before the sale, that a gem is treated, laboratory-grown or an imitation.