|
|
ISO Grading Standards Analysis
May 31, 1996 12:55 PM
|
|
|
First Step Leaves Much to Resolve
by Elly Rosen
As a first step towards standardizing diamond grading procedures,
terminology and reporting among the world's laboratories, the
International Organization for Standardization (ISO) has issued a
"Technical Report," TR-11211, entitled "Grading Polished Diamonds -
Terminology and Classification." Although the Gemological Institute
of America (GIA) is listed among the four groups that compiled the
report, few in the American gemological community seem knowledgeable
of this attempt at standardization and even fewer see much of a future
for the ISO standards in the United States.
Initial concerns raised by American diamond dealers and gemologists
are acceptance, policing, enforcement and abuse. Many also seem to be
leaning towards the position that if the GIA standard "ain't broke,
why fix it?" It is therefore important to stress that this release is
merely an offering for international discussion and not even a first
proposal of an actual standard.
The report's 15-page first edition was published on December 15,
1995 and was prepared by ISO Technical Committee (ISO/TC) 174,
Jewellery. The main task of technical committees is to prepare
international standards, but in exceptional circumstances, a technical
committee may propose publication of a Technical Report of one of
three types. ISO/TR-11211 is a Type 1 Report which is published "when
the required support cannot be obtained for the publication of an
International Standard, despite repeated efforts."
Trade Comment Sought
As to input from the trade, the forward of the report states that
"This Technical Report is subject to further consideration and members
of WG 2 and others have already provided relevant proposals. Its
adoption will give members of the industry an opportunity to discuss
and comment . . ."
ISO/TC 174's home base is ISO's member body, the Deitches Institute
fer Normung (DIN) in Berlin and TR-11211 was compiled by:
Confederation Internationale de la Bijouteria, Joaillerie, Orfovrerie,
des Diamants, Perles et Pierres (CIBJO); GIA; International Diamond
Council (IDC) and Scandinavian Diamond Nomenclature (Scan.D.N.).
Will "Standards" Bring Uncontrollable Abuse?
Some laboratories and dealers are concerned that adoption of this
international standard will allow small labs to stamp their grading
reports as having been done in accordance with "ISO International
Standards" with no one to police them and make sure that they have
been. They see this as a possible step backwards from the current
situation in which we have different but definable and verifiable
laboratory standards.
Hertz Hazenfeld, of Hazenfeld-Stein, NYC, who chairs the
gemological committee of New York's Diamond Dealers Club (DDC) felt
that the European diamond community might adopt such a common standard
but that Americans are content with the GIA standard and would stay
with it. He told this writer that, "Each laboratory has always had
defined standards and their reports have had their own level of
acceptability which is determined by the market. There is every
reason to feel that Americans will retain their open market system."
Jerry Eherenwald, President of the International Gemological
Institute (IGI) said that "We have always based our grading on GIA
standards and we will continue to follow GIA's lead."
David Atlas, President of Accredited Gem Appraisers (AGA), in
Philadelphia, lauded the current GIA standard. He said that, "We have
always had a standard that we could verify and check. You might not
always agree with the judge, but at least we've always had an
identifiable 'Supreme Court' we can turn to in case of a grading
dispute or a suspicious report."
As of the writing of this article Thomas Yonelunas, CEO of GIA's
Gem Trade Laboratory (GTL) and NY DDC President Eli Izakoff could not
reached in time to comment on the ISO report.
Gap Remains Between Trade and Lab Practices
TR-11211 is a major effort to standardize current procedures of
laboratories functioning around the world and it does address many
issues that have been long overlooked. It gives comprehensive
coverage to grading issues of concern to laboratories, gemologists and
perhaps, gemological appraisers. But, TR-11211 does little to close
the gap between the traditional grading procedures of the grass-roots
wholesale and retail diamond trading community and those of the gem
labs attempting to serve them.
The biggest gap remains in the difference between clarity grading
with a 10x hand loupe as opposed to a high-magnification binocular
zoom microscope. Most labs study a diamond under the microscope and
then "make the grading call" with a loupe. While this might be a
sincere effort to replicate the way traditional diamond dealers
clarity-grade in the reality of the marketplace, many feel that there
is often a major disparity in the results.
It doesn't take much imagination to see the problem. Although
loupes are in the hands of knowledgeable dealers with trained eyes,
the "visibility" of a pinpoint inclusion is quite different when using
only the loupe from beginning to end. Once the inclusion has been
spotted with the binocular microscope and its built-in dark-field
illumination, it will usually be easier to see with a loupe afterwards
- especially if the grader zoomed the microscope to a higher power
during the initial inspection. This microscope-first and then-the-
loupe procedure doesn't seem to be the true equivalent of a loupe
grade by a knowledgeable diamond dealer.
Loupe vs. Scope Distinction Not Made
The ISO standards do not address clear reporting of this
distinction. In fact they appear to foster old confusions by stating
that clarity grades should be assigned by a "trained observer with
normal eyesight using achromatic and aplanatic 10x magnification . .
." There is no mention of distinctions or of disclosure of grading by
hand loupe versus a microscope.
The report also calls for clarity grading to be performed "under an
artificial source of light . . . (CIE standard illuminant)." While
this might be a step forward in standardizing clarity grading it could
result in a short-term widening of the gap between traditional dealer
grading and that of the labs.
Reconciliation of Clarity Grading Conflicts
The report expands on current U.S. lab clarity nomenclature by
defining VVS as Very Very Slightly Included/Very Very Small
Inclusions. The same option of using the "S" to mean either Slightly
or Small carries over to the VS and SI grades.
As to the complex and confusing issue of eye-visible inclusions,
the report reconciles new and old-world terms but then seems to take
one approach that serves to standardize while at the same time fosters
a current problem of ambiguity.
The U.S. lab "I" grades are to be read as either "Included 1-3" or
"Pique 1-3" (P1-3). This should be welcomed by many, including
myself, who prefer pique- especially for melee.
These "I"/"P" grades are then described by their degree of
prominence under 10x magnification ("prominent" "very prominent"
"extremely prominent"). This is a departure from the way American
gemologists were taught to approach the issue. GIA graduates seem
more used to looking at the I1-3 grades based on the extent of
visibility to the trained naked eye. The report introduces these
grades with the additional statement that "They are also visible,
easily visible to very easily visible face up with the unaided eye and
may affect brilliancy."
Ambiguity Remains for Low Clarities
This inverted approach to the "I1-3" grades might help clarify the
little understood reality that most labs will give "SI" or better
grades to eye visible inclusions, depending on the size and shape of
the diamond. Indeed, the introduction to the "I/P" grades states that
"Under certain circumstances, internal characteristics/inclusions may
also be visible face up to the unaided eye in higher grades."
Unfortunately, the report then stops short of providing any insight
into just how this major area of ambiguity is going to be
standardized.
Tom Tashey, President of the Los Angeles based European Gemological
Laboratory said that, "This difficult area between the SI and I grades
was the reason for our establishing an SI3 grade. The selling and
buying communities welcome opportunities to reduce ambiguity in
diamond grading."
Combined Grades are allowed under the report. VVS, VS and SI
without the two-step numeric breakdown may be used for diamonds under
0.47 cts.
Some Other Issues
* Color Grading - The Report reconciles GIA, CIBJO/IDC and
Scan.D.N. grades by calling for the use of the GIA letter grading
protocol, along with descriptive phrases in English, German, French
and Italian and even includes a conversion chart for the Scan.D.N.
"River" through "Cape" descriptions.
Color Grading Variables:
- "Descriptions indicating the presence of brown or grey may be
included for Grades I and below."
- "Combined letter grades including and below M . . . may be
used as well as a two grade letter range above M."
- "For diamonds weighing under 0.47 ct. the combined grades
of D and E "exceptional white", F and G "rare white" may be
used."
Color Vision - This long overdue and critical subject is
scarcely and poorly addressed with, "The determination is
carried out by a trained observer with normal eyesight and color
discrimination . . ." Hopefully, any International Standard
that might be adopted would be clearer on standards for "normal
eyesight" and "color discrimination" as well as for "color
vision."
[More comprehensive treatment on issues related to diamond
clarity and color grading can be found in two prior articles by
Elly Rosen: "The Plain Truth About Diamond Grading," RDR,
November 4, 1994 and "Color Grading Has Shades of Gray," RDR,
December 2, 1994.]
* Proportion grades - The report does not provide for
specific numerical parameters for the grading of the quality
of diamond cut. It does provide for descriptive elements
of cut. "Average" measurements and/or percentages are called
for when describing: girdle diameter; crown height; pavilion
depth; culet size; total depth height and even for the table
size. Girdle thickness is to be described by noting the
minimum-maximum or the average in terms of a percentage or with
standard descriptive terms of "extremely thin, knife edge" to
"extremely thick".
* Synthetic and treated diamonds as addressed in the report
-
- Synthetic diamonds must be clearly referred
to as "synthetic diamond."
- "All diamonds which man has drilled with a
laser should be referred to as "clarity grade influenced by
laser drilling treatment."
- "Any other treated diamonds, including those
which have been coated or filled by man, cannot be graded."
- "Those stones that owe their color to
artificially produced irradiation or any other form of
treatment should only be described by their color hue, for
example "yellow treated color". The term "fancy" should not be
used."
- Assembled stones "must be clearly identified and shall
not be graded."
[More on the subject of grading and appraising treated diamonds
can be found in a prior article on the subject by Elly
Rosen entitled "Appraising the Yehuda Controversy," RDR, February
3, 1995.]
The ISO "is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International
Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for
which a technical committee has been established has the right
to be represented on that committee. International
organizations, governmental and nongovernmental, in liaison
with ISO, also take part in the work. ISO collaborates
closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization."
Efforts to standardize terminology and classification of
polished diamonds is conducted within ISO/TC 174's Work Group
(WG) 2 which was set up to clarify questions on specific aspects
of polished diamonds. At this point the WG 2's work has
been submitted to the technical committee for consideration with
full agreement on some aspects not yet achieved. According
to the report's forward, "In particular, agreement is needed on
the question of proportion, and further work is required for
test methods and concerning the color of fancy colored
diamonds."
Elly Rosen is a freelance gemological appraisal principles
consultant in Brooklyn, N. Y. His new Appraisal
Information Services (AIS) offers subscriptions to appraisers
for: appraisal consulting; the Monthly Appraisal Reporter
(appraisal principles newsletter) and gemological appraisal
supplement; appraisal report "boiler-plate" and formats for
various types of appraisals as well as an audio tape lecture
series on appraisal issues and a glossary of professional
appraisal terminology. Mr. Rosen was one of the principle
developers and instructors of the Certified Appraiser of
Personal Property program (CAPP) from 1982 to 1993 and has
written new and advanced appraisal courses for the new appraisal
program of the American Gem Society's Jewelers Education
Foundation (AGSJEF). He is also a member of the JVC's ATF and
was one of the principal developers of the new JVC Guidelines.
AUTHOR'S NOTE: As an adjunct to this article, Mr. Rosen has
agreed to accept telephone questions on the subject, within
reason, from RDR subscribers. He can be reached at (718) 692-
1975. Mr. Rosen is also available to answer questions in the
RapNet "Appraisals" conference and via RapNet e-mail to his
RapNet user id EROSEN or via InterNet EMail to
erosen@rapnet.diamonds.com.
|
|
|
|
|
|
|
|
|
|
Tags:
CIBJO, GIA, IGI, JVC, Laboratories, Labs, United States
|
|
|
|
|
|
|
|
|
|
|