low) that showed distinctive asymmetry: a strong
onset of fluorescence at ~500 nm, a peak maximum
at ~525 nm (±7 nm), and a long tail on the highwavelength
side. Most of the spectra in figure 5 also
showed a secondary peak at ~450 nm.
The yellow-green diamonds predominantly
showed weak-to-moderate fluorescence intensity at
~445 nm and very strong asymmetric fluorescence
centered at ~525 nm. Figure 6 shows fluorescence
spectra at different excitation wavelengths for a
green-yellow diamond that is representative of all
seven diamonds of this color range.
The six brown diamonds showed weak-to-moderate
fluorescence spectra with peaks centered at
510–532 nm. Figure 7 shows fluorescence spectra for
one sample (GIA 12172-5b) obtained from the spec