Photoluminescence spectroscopy in diamond analysis primarily involves which observation?

• A. Photoluminescence spectroscopy uses only visible light to measure color.
• B. Photoluminescence spectroscopy measures infrared energy absorption.
• C. Photoluminescence spectroscopy measures diamond weight.
• D. Photoluminescence spectroscopy examines light emitted by a diamond after exposure to a high-power laser.

Answer: (D)

Photoluminescence is about what the diamond emits after it is excited by light. In this technique, a high-power laser shines on the diamond, exciting electrons at defect centers in the lattice. As those excited electrons relax back to lower energy levels, they emit photons. The spectrum and intensity of this emitted light reveal information about the diamond’s impurities and defects, which helps identify color origin, quality, and certain characteristics.

This makes the observation specifically about the light produced by the diamond after excitation, not about absorbing infrared energy or measuring weight, or simply using light to infer color.