Irradiation

Treatments & Enhancements

Definition

The exposure of a gemstone to high-energy radiation (gamma rays, neutrons, or electrons) to alter its color by displacing electrons and creating color centers within the crystal lattice.

Detailed Explanation

Irradiation is used to create blue topaz from colorless topaz — one of the most commercially common treatments. Blue diamonds, whether naturally colored or irradiated, owe their color to structural defects (the N-V center) that absorb red light. Irradiated stones are sometimes subsequently annealed (gently heated) to shift the resulting color. In most jurisdictions, irradiated gems must be disclosed; residual radioactivity in neutron-irradiated stones requires a quarantine period before sale. Lab testing using thermoluminescence can sometimes detect irradiation history.

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