 Diamond
Grading Report Parameters
A diamond grading
report will commonly include
a plotted diagram of your
diamond and significant
characteristics, including
the 4Cs (cut, color, clarity
and carat weight). The report
will also describe the diamond’s
shape, exact measurements,
proportions and depth percentages
as well as grade the polish
and symmetry. It should
also comment on the characteristics
like fluorescence, raining,
and any imperfections in
the diamond. Please note:
a grading report does not
include an appraisal or
any kind of statement of
monetary worth of the diamond.
Grading reports simply state
the scientific facts of
your diamond that can be
evaluated by highly standardized
criteria.
It is important to refer
to the certificates issued
by GIA (gemological Institute
of America) and AGS (American
Gem Society) as
Diamond
Grading Reports.
This is an important distinction,
one that probably came years
after GIA's lab started
offering reports. However
generally the diamond industry
still uses the terms certificate
and grading report interchangeably.
The term certificate or
cert for short. A Diamond
Grading Report is a statement,
issued by an independent
Gemological Laboratory,
that at the time of evaluation,
the Diamond in question
has been examined by experienced
Diamond Graders, using various
gemological instruments,
and determined to contain
the characteristics as stated
in the Report.
Grading reports do not give
a value; appraisals do that.
They give an independent
expert opinion on quality
for loose or unset gems.
Most grading institutes
have labs or services worldwide
and do not sell diamonds.
A reliable Diamond Certificate
consists of the following
important parameters:
|
Date of the Report |
Sometimes the diamond
can get damaged
before the certification
date. Therefore
it is important
to ask the retailer
to explain the similarity
of the purchased
diamond with that
in the certification.
|
|
Unique ID # |
The Identification
Number is often
laser inscribed
on the diamond,
if not, one can
always request the
jeweler for the
same. IGI uses the
terminology "Diamond
Identification Report"
although it is recognized
as a certificate.
Every lab has a
certificate (or
"report") number,
which identifies
a diamond uniquely.
The Lab keeps an
internal copy of
everything shown
on the certificate,
and also additional
information. The
certificates can
thus be re-issued
when they are lost.
|
|
Issuer of the Report |
The Laboratory from
where the certificate
is issued should
be well constituted
and respectable. |
|
Origin |
The Diamond’s origins;
whether natural
or enhanced, should
be verified from
the report. Generally,
fractured diamonds
are not graded by
labs, but laser
drilled ones are
accepted. |
|
Carat Weight |
Carat weight of
the diamond should
be accurately written
in the report. Diamonds
are weighed to the
thousandth of a
carat with a digital
measuring device.
On the Report, the
weight is rounded
off to the hundredth
of a carat. |
|
Shape and Cut |
These parameters
are also mentioned
in the report, and
therefore should
be verified. Shapes
can be categorized
as Round, Pear,
Heart, Oval, etc.
Cutting Styles can
be categorized as
Brilliant, Marquise,
Emerald, Princess,
Step and Mixed.
|
|
Measurements |
Accuracy in measurement
is very important
in identification
of a diamond, as
no two diamonds
can have exactly
the same dimensions
and weight. This
is generally measured
in millimeters,
typically to a hundredth
of a millimeter.
|
|
Proportions |
A diamond cut in
well planned proportions
exhibits more brilliance
and fire. Therefore
it is as important
as clarity or color
grades. The proportions
of the diamond can
be the summed up
as its depth, and
its table .Both
are expressed as
percentage figures.
Depth percent refers
to the percentage
depth of the Diamond,
measured from the
table to the culet,
relative to the
width of the stone.
|
|
The 4 Cs |
Diamond buyers should
know the 4Cs: cut,
color, clarity,
and carat weight.
|
|
Fluorescence |
Fluorescence refers
to a diamonds reaction
when exposed to
long wave ultraviolet
radiations. Too
much fluorescence
can make a Diamond
less desirable.
|
|
Plotting |
A Plot is a graphical
representation of
the imperfections
present in the Diamond.
Every diamond has
unique characteristics
like fingerprints.
By plotting its
characteristics,
and combining this
with the physical
measurements of
a Diamond, a Lab
can uniquely identify
each stone. This
plot is a guideline
for the Grader in
the event that a
customer returns
to the Lab and requests
verification on
his diamond purchase.
Internal characteristics
are plotted in red,
and external characteristics
are plotted in green.
|
|
Comments |
Comments are used
to describe characteristics
which are not discussed
elsewhere on the
certificate, or
to mention the items
not plotted or shown.
For example, "insignificant
external details
are not shown" is
one of the common
comments. |
|
Comments |
Reading a certificate
should be learnt
carefully and is
helpful in diamond
purchase. However,
purchasing a diamond
should not be solely
based on its certification.
Some diamonds can
look beautiful even
if they don’t seem
good from their
certification. |
Read
more...
Diamond Certificate
Helpful for Insurance
A grading report, or "certification"
does not add value to your
stone, and not having one
does not detract from its
value. Rather, it assures
the value of the stone.
It proves that you got what
you paid for. It's also
helpful whenever you need
to identify your diamond
- if it is ever lost or
stolen, or if you give it
to someone to do repair
work and you want to make
sure they gave you your
diamond back.
More about Diamond
Certification
The Four C’s mentioned above
are the basic guidelines
for buying a good quality
diamond, but these Four
C’s can only be deciphered
by expert gemologists. They
use highly sophisticated
spectrometers and other
necessary equipment required
for the inspection of diamonds
in laboratories. A document
is generally issued by such
laboratories explaining
the vital characteristics
and grading of the 4 C’s.
The 5th C refers to Certification.
It provides details about
the critical parameters
that affect the gem’s quality,
value and appearance. Certification
is therefore very important
for diamond experts for
verification of their purchase.
Read
more...
|
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