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oday, yellow diamonds are among the most
widely encountered of the “fancy color” dia-
monds (figure 1). From 1998 to the present,
GIA has issued grading reports on more than
100,000 yellow diamonds, by far the most common
of the fancy-color diamonds submitted to our labo-
ratory. In 2003, for example, 58% of the diamonds
submitted for GIA Colored Diamond Grading
Reports or Colored Diamond Identification and
Origin of Color Reports were in the yellow hue.
Nevertheless, these represented only 2.4% of all
diamonds submitted for various grading reports that
year. The dichotomy between being common
among colored diamonds yet relatively rare overall
has created a mix of information and sometimes
erroneous assumptions about yellow diamonds. In
addition, although information about their “origin
of color” or unusual characteristics (see below) has
been documented over the years, little has been
published about their color appearance and its rela-
tionship to color grading (one exception being
Hofer, 1998).
This article presents data on more than 24,000
fancy-color yellow diamonds that were examined
by the GIA Gem Laboratory during the years 1998
and 2003. While our main concern in this study was
gathering information to characterize the gemologi-
cal and spectroscopic properties of the entire popu-
lation of samples, we were also interested in identi-
fying any trends in size, color grade, or clarity grade
among the yellow diamonds submitted to us that
might be revealed over time. To that end, we select-
ed a sample population from these two years sepa-
rated by a five-year span.
Following a brief review of the literature on the
geographic sources, cause of color, and other physi-
cal properties of fancy-color yellow diamonds, this
article will focus on expanding the published infor-
mation about these diamonds by documenting and
88
YELLOW DIAMONDS GEMS & GEMOLOGY SUMMER 2005
CHARACTERIZATION AND GRADING OF
NATURAL-COLOR
YELLOW D
IAMONDS
John M. King, James E. Shigley, Thomas H. Gelb, Scott S. Guhin, Matthew Hall, and Wuyi Wang
See end of article for About the Authors and Acknowledgments.
GEMS & GEMOLOGY, Vol. 41, No. 2, pp. 88–115.
© 2005 Gemological Institute of America
To better understand the yellow diamonds currently in the marketplace, as well as identify possible
changes in their trends seen over a five-year period, researchers at the GIA Gem Laboratory ana-
lyzed gemological data collected on more than 24,000 natural-color yellow diamonds examined
in the calendar years 1998 and 2003. These data included color grade, type of cut, clarity grade,
weight, ultraviolet fluorescence, and UV-visible and infrared spectra. Among natural-color colored
diamonds, those with a yellow hue are some of the most abundant; even so, they are much less
common than the colorless to light yellow diamonds associated with GIA’s D-to-Z color grading
scale. Since the yellow color is a continuation of the gradation of color associated with the D-to-Z
scale, there can be misconceptions about the color grading, which involves different procedures
from those used for D-to-Z grading. The grading and appearance aspects, as well as other charac-
teristics of yellow diamonds, are discussed to clarify these differences. The authors have also identi-
fied five subgroups of type I yellow diamonds, which (with some overlap) are characterized by rep-
resentative spectra and color appearances.
T
Gia Yellow Diamond Color Chart
source: northarrowminerals.com
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