prior fluorescence studies performed at GIA
found that about 35% of near-colorless gem
diamonds fluoresce to long-wave UV radiation,
with 97% of those diamonds showing blue fluorescence
(Moses et al., 1997). However, colored
diamonds more commonly show fluorescence, and
in a wider variety of colors (e.g., figure 1). Given the
methodology with which fluorescence is typically
observed, it is sometimes difficult to determine the
underlying mechanism of this behavior and, specifically,
the influence of the natural, synthetic, or
treated nature of the diamond on its fluorescence.
Becquerel (1868) and Dyer and Matthews (1958)
were among the first scientists to study the fluorescence
properties of diamonds. Dyer and Matthews
studied the luminescence of the 415.5 and 504.0 nm
systems (now identified as the N3 and H3 defects;
see, e.g., Collins, 1982a) and found that these features
were related to blue and green fluorescence, respectively.
A review by Fritsch and Waychunas (1994)
detailed the observed fluorescence and phosphorescence
of diamonds according to their bodycolor.While a large number of peaks and defect centers
have been chronicled in natural diamonds using UVVis
absorption, cathodoluminescence, and photoluminescence
spectroscopy (see, e.g., Zaitsev, 2001),
spectral data for fluorescence and phosphorescence
are limited in the gemological literature, since luminescence
is typically described by visual observations
(again, see Fritsch and Waychunas, 1994). However,
visual assessment of fluorescence and phosphorescence
tells only part of the story. The color discerned
by the unaided eye may represent a combination of
two or more wavelength regions. For example,
Anderson (1960) asserted that although most fluorescing
diamonds appear to luminesce blue, a yellow
or green component may be present but masked by
the stronger blue emission. He used color filters and a
spectroscope to try to identify some of the relevant