Photoluminescence Mapping is described as a PL mapping technique?

• A. A method to map the refractive index across a gem.
• B. A way to measure fluorescence under UV light.
• C. A spectroscopy technique that collects PL data across the entire surface of a diamond, showing subtle distinctions in defect concentrations.
• D. A technique to photograph a diamond under polarized light.

Answer: (C)

Photoluminescence mapping is a spectroscopy approach that excites a diamond and collects the emitted light as a function of position across the diamond’s surface, producing a map of luminescent centers. By scanning or imaging across the surface, it reveals subtle variations in defect concentrations—information not evident from a single-point measurement. In practice, a UV or laser excitation source induces photoluminescence, and the detector gathers emission data across many points to build a spatial map of the diamond’s luminescent features. This makes it a true mapping technique that highlights defect distribution rather than just a simple fluorescence readout or a polarized-light photograph.