Paper No. 4
Presentation Time: 9:45 AM


ARDON, Troy, Identification, Gemological Institute of America, 5355 Armada Drive, Carlsbad, CA 92008 and MAGANA, Sally, Gemological Institute of America, Carlsbad, CA 92653,

This study gives a detailed analysis of the spatial distribution of optical centers within a IIb diamond. Using the mapping functionality of an infrared microscope, we profiled the boron distribution of a rough type IIb diamond. The thin plate allowed transmission IR spectra to be collected at 100 μm intervals across a 1.3 mm X 1.7 mm area. Photoluminescence (PL) spectroscopy using 488 nm and 514.5 nm lasers was also collected at analogous locations so that PL-activated centers including the 3H (503.5 nm), NV0(575 nm), GR1 (741.2 nm) and the currently unknown peak at 776.4 nm could be chronicled as well. Visible features on the rough diamond along with a scale bar on the PL microscope helped coordinate data collection from PL at identical locations as FTIR.

The data showed a strong gradient in boron concentration across the collected area and a concurrent gradient in the 776.4 nm peak intensity (when normalized to the Raman peak). The NV0peak showed an inverse relationship while the 3H peak intensity showed two local maxima in the regions where the 776.4 nm peak and the 575 nm peaks were greatest. The GR1 showed a less pronounced correlation with the other peaks examined or the boron concentration.

Comparison of the spatial maps for the boron concentration and PL peaks show that in this sample, it appears the NV0center segregates into areas with lower boron concentration. Composition of the 776.4 nm peak is currently unknown although we hypothesize it is vacancy related and based on the data here, it correlates well with boron concentration so we propose that 776.4 nm peak is a [B-V] complex.

Effects of annealing on the spatial distribution of these centers will also be presented.

  • GSAPosterBoronConc.pptx (3.1 MB)