Fall 2000 Gems & Gemology - Gemfrance

I
New Diamond Treatments: What Do
They Mean for the Gemological Laboratory?
n each of the last five issues of Gems & Gemology, we
have published articles on the high pressure/high temperature
(HPHT) annealing of diamonds to modify their
color. This is arguably one of the most serious challenges
the diamond industry has ever faced. Most of these articles
have dealt with the decolorization
of diamonds as represented by
the GE POL process. The paper by
Christopher Smith and his colleagues
in the present issue is the most recent
contribution. It provides some important
new data on the characteristics of
GE POL diamonds before and after
processing.
What, though, does all this mean
for the jeweler and gemologist? In particular,
what do all these developments
mean for a laboratory that is
entrusted with the responsibility of
identifying these and other treated or
synthetic diamonds?
The role of the gemological laboratory
has changed in many ways over Robert Shipley Jr. demonstrates
the past decade. Not only have the GIA’s state-of-the-art laboratory
techniques and instrumentation for equipment in 1938.
gem identification become more
advanced, but the methods and steps in diamond grading
have become much more extensive and sophisticated.
The new developments in treatments to diamonds and
the further advancement of synthetic diamond growth
methods have made it necessary for a gemological laboratory
to become well equipped and to continually modify
the screening methods used to detect such diamonds.
While I cannot speak for all laboratories, there have
always been processes incorporated into the servicing
procedures of the GIA Gem Trade Laboratory to meet
such challenges as synthetics, coatings, fillers, laser
drilling, and irradiation. More than a dozen additional
detection techniques and instruments have been added
to this process in the last five years alone.
Overall, the GIA system has been designed to ensure
accuracy, efficiency, and client anonymity throughout
the grading process. There are meticulous electronic
routing techniques that guide a diamond through the
laboratory, which include numerous steps that capture
well over 400 separate and distinct pieces of gemological
and scientific information.
After careful weighing and measuring, each diamond
is processed through a series of instruments designed to
differentiate natural from treated and synthetic diamonds,
as well as to detect and distinguish diamond
types. These include, but are not limited to, the De
Beers DiamondSure, short-wave ultraviolet fluorescence
transparency devices, and proprietary spectroscopic
instruments designed to measure the presence and level
of trace elements, such as nitrogen, in each diamond.
All diamonds that are determined
to be type II are then further screened
by GIA’s most experienced gemologists
and research scientists. Some of
the techniques and instruments
employed include UV-Vis-NIR spectroscopy,
high-resolution infrared
spectroscopy, and (low temperature)
Raman analysis to determine key
photoluminescence features. Results
from these analyses are then compared
with our extensive database on
known HPHT-annealed diamonds
and untreated type IIa’s.
Based on our careful examination
of well over 2,000 GE POL diamonds
to date, we believe that the vast majority
of diamonds that have been decolorized
by HPHT annealing can be
identified through their properties, the
laboratory’s grading and research experience,
and the data archived in the laboratory’s Horizon
operations and management information system.
The proliferation of diamond treatments also raises
questions about the fair and accurate representation of
these products to tradespeople and consumers alike.
There are legitimate markets for enhanced diamonds
and an important need for consumers to know exactly
what they are purchasing. As a result, we are currently
reviewing our reporting policy for some enhanced diamonds
and the scope of services we offer.
Yes, there are challenges to the way laboratories must
now operate. We must gather more information, using
more sophisticated instrumentation, in a process that
often requires more time and a tremendous investment
in equipment and personnel. Because many of these new
treatments cannot be detected with standard gemological
equipment, we are all serving a much broader constituency.
Nevertheless, we believe that with solid
research, with continued cooperation from the trade, and
with flexibility and ingenuity, we and other wellequipped
gemological laboratories will be able to continue
to meet the needs of both the trade and the public.
William E. Boyajian, President
Gemological Institute of America
Editorial GEMS & GEMOLOGY Fall 2000 189