Irradiation is defined as which description?

• A. Exposure of a material to radiation.
• B. Chemical treatment with acids
• C. Exposure to heat during annealing
• D. Physical abrasion

Answer: (A)

Irradiation means exposing a material to radiation. In gemstones this process uses high-energy particles or photons (like gamma rays or electrons) to alter the crystal lattice and create color centers, changing the stone’s color. Sometimes a subsequent heat treatment (annealing) is used to stabilize or adjust the resulting color, but irradiation itself is defined by the exposure to radiation. The other options describe chemical treatment with acids, heating in a way that’s not specifically irradiation, or physical wear, which are different processes altogether.