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Ideal Cut Diamonds: What's
it all about?
"The notion that there's something special about one
set of proportions which is not produced by another set, just doesn't hold up."
Dr. Mary Johnson, Manager of GIA Research and Development in Carlsbad, CA.
At A. Fishman & Son, we focus on
offering our customers "well
cut" diamonds that are pretty and reflect full brilliance and fire.
What do we mean by "well-cut" and how do we distinguish our cut from
"ideal" cut (or "ultra ideal") diamonds? While we own
and offer many diamonds which have
proportions which would be considered "ideal" cut, they are all very
fine cut diamonds. However, unlike our diamonds which fall within the "ideal
cut" proportions, there are many diamonds which fall within those
"numbers" but whose cut is in fact poor and those diamonds are not
pretty diamonds. Like the Gemological Institute of America
("GIA") (see below), we do not feel
it is appropriate to use the term "ideal," as it reflects the concept
of "perfect." And we do not believe that all diamonds which fall
within the "ideal" cut proportions deserve the connotation that the
term implies.
Ideal Cut
An “ideal" cut diamond refers to a round diamond
cut to a specific set of cutting guidelines that delineate the proportions that
are assumed to give a round diamond the greatest amount of fire and brilliance.
There is a tremendous amount of information, some good and some very misleading,
regarding what an "ideal" cut diamond should look like and what
proportions it should be cut to.
One of my biggest issues with the concept of
"ideal" cuts is this. If an "ideal" cut diamond reflects a
single set of cutting proportions which are "perfect," how is it that the depth and table
percentages can have such a wide range? The traditional proportions often
quoted for ideal cut - and "established" by the American Gem Society ("AGS") is a table percentage of 52.4-57.5% and a depth percentage
of 58.4-62.9%. This set of proportions assumes that any two
diamonds whose proportions are cut within these ranges is equally pretty and
look alike. Is this really possible? Is it possible that two diamonds which fall within this
range, but at the extremes, really look the same? In our opinion, and the
opinion of the GIA, this is patently false. A diamond of 60 depth
and 57 table may be a pretty diamond, but, in our opinion, a diamond of 62.9 depth and 53
table is not. And it is obvious to any one who thinks through the issue
that these two diamond will not look the same to the eye.
GIA Research
and Conclusions
Recently, the GIA has undertaken research to determine whether
the noted cutting proportions of "ideal" cut stones actually produce
the maximum fire and brilliance in a round diamond compared to other cutting
proportions.
In the Fall 1998 Issue of the GIA's Gems and Gemology,
the GIA published the first of its articles regarding cut in its landmark
Modeling
the Appearance of the Round Brilliant Cut Diamond: An Analysis of Brilliance.
The synopsis of this article states in relevant part:
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"The results of this study suggest
that there are many combinations of proportions with equal or higher WLR
(weighted light return) than the traditional 'Ideal' cuts. In addition,
they do not support analyzing cut by examining each proportion parameter
independently." |
In fact, the research in this case showed that round diamonds
with larger tables (64-66%) and with shallower crown and pavilion
angles (not the 35.8 degrees on the crown and the 43 degrees on the pavilion
often mentioned), delivered MORE light return than traditional
"ideal" cut proportions.
In an editorial in the same issue (see
Demystifying
Diamond Cut) the President of the GIA, William E. Boyajian, made a
very important statement regarding the use of the term "ideal
cut." He stated:
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"We also know that
there are many combinations of proportions that yield equally attractive
round-brilliant-cut diamonds. In fact, we know that diamonds can be cut
in a fairly wide range of proportions to yield the same high light
return, which can lead to better utilization of the rough and a better
fit with the myriad tastes that exist in the global marketplace.
Finally, we know from our extensive historical
research on cut that there have been numerous claims to a single set of
'Ideal' proportions in round-brilliant-cut diamonds. The derivation and
use of the term 'Ideal' is thus confusing at best, but not unlike
that of 'blue-white' and 'perfect' decades ago. Although it is not GIA's
role to discredit the concept of an 'Ideal' cut, on the basis of our
research to date we cannot recommend its use in modern times."
(emphasis added) |
In the Fall 2001 Issue of the GIA's Gems and Gemology,
the GIA published its second article regarding cut in its article
Modeling
the Appearance of the Round Brilliant Cut Diamond: An Analysis of Fire, and More
About Brilliance.
As Mr. Boyajian states in his editorial summarizing this article:
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"The
authors conclude that there is no easy way to characterize the
“best” cut in round brilliants for either brilliance or fire.
Rather, it is the complex interaction of multiple proportions, involving
all of a diamond’s facets, that must be considered in the assessment
of these key appearance aspects. Furthermore, there is now even more
evidence to support the conclusion that there is no one “best” cut
for a round brilliant diamond." (emphasis added) |
In the Spring 2002 issue of the GIA's The
Loupe, the GIA published an article entitled The Science of Cut.
This article, following up on the two previously mentioned articles, confirms
that there really is no single best cutting proportions for a round
diamond. This article states in relevant part:
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"All
of a diamond's quality factors play a part in a polished round
brilliant's overall appearance, but the role proportions play in the
quality of diamond cut has historically been the least understood....
Early
on, researchers at GIA expected their results to corroborate one or more
of the existing cut grading systems, but their work to-date indicates
the underlying approaches of most existing systems are not
substantiated by the data.
The
industry has for decades embraced the concept that an extremely
limited set of round brilliant diamond proportions produce
maximum brilliance and fire so, in terms of an evaluation of cut, any
deviation from this set of proportions would impact the appearance
materially. It believed
that the further the proportions deviated from this limited set of proportions,
the greater the impact was on the appearance of the diamond.
Preliminary
findings of the GIA's diamond cut research indicate otherwise...They
discovered that there are many proportion combinations that can yield
equally strong-performing diamonds...The notion that there's
something special about one set of proportions which is not produced by
another set, just doesn't hold up." (emphasis added) |
Finally, in the Fall 2004 Issue of the GIA's Gems and Gemology,
the GIA published its third article regarding cut in its article
A Foundation for Grading the Overall Cut Quality of Round Brilliant Cut
Diamonds. In this article, the author ties the various
elements of the GIA's studies together. Some of the main findings from the
GIA's research discussed in the new article, as summarized in the GIA's
editorial,
Unlocking the Secrets of the Fourth C are:
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Proportions need to be considered in an
interrelated manner. The combination of
proportions is more important than any individual proportion value.
Individual proportions must not be assessed on their own. It is the
complex interrelationship of individual proportions that matters most in
the face-up cut appearance and overall cut quality of a diamond.
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There is no one set of proportions that yields the
most beautiful diamond. Similarly, the long-held view that expanding
deviations from a fixed, arbitrary set of proportion values produces
diamonds with increasingly poorer appearances is simply not valid.
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Attractive diamonds can be manufactured in wider
range of proportions than would be suggested by historical practice or
traditional trade perception.
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Viewing environment plays an important role in
diamond appearance -- to be attractive, a diamond should look good in
realistic environments.
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Personal and international market
preferences should be accounted for. Diamonds with different
appearances can be found within each cut grade, so individuals need to
look at the diamond itself, not just the grade -- to choose the one they
like best.
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What does all of this mean to you, the consumer? It
means that you need to rely on the expertise of a diamond source that
understands what diamonds are all about, that can evaluate the merits of a
diamond beyond the mere statistics that appear on a certificate, and that can
guide you to the right diamond for you. That diamond source has to have
the experience which only time and generations of buying diamonds can give
you. After all, if you never have to put your own money down (like the
hundreds of internet sites who simply collect nationally available diamond
lists), how can one really understand which diamond is desirable and which one
is not!
At A. Fishman & Son, we have 63 years, and three
generations of experience in buying diamonds and selling them. We have
always put our money where our mouth is and invested in "pretty" diamonds which
will please our customers. It is that experience which you can count on to
assist you in your diamond selection. (Back to top)
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800-223-0155
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