Home Page
| Why from Five Star | Why
GIA | Personal Info on Owner
| Refund Policy | Do's and Don'ts | Four C's | Anatomy
of GIA | Which Certificate | Current
Debates | In-Town or Out-of-Town | Ideal
Cuts really Ideal |
Round Inventory
| Fancy Inventory | This
Week's Special |
Email Us
Anatomy of a GIA Certificate
The GIA diamond grading report is a simple, straightforward document
which represents decades of concentrated effort to create a grading system
which imparts as much information as possible and is reproducible to a
degree that it makes the most discerning diamond dealer satisfied. It is
the pedigree that goes with the diamond. It is also very important to have
because in case of a loss, the insurance company must replace the stone
with like kind and quality - another certified stone. You do not have to
be at the mercy of your jeweler in this situation.
There are several parts to the document:
1. An original GIA diamond grading report will have the Gemological
Institute of America logo in the upper left. GIA GEM TRADE LABORATORY will
be at the top of the document, with addresses and phone numbers, and the
document will be laminated.
2. The report will have a number. The position of this number will
vary depending on the date issued. Recent documents have the number in
the upper left hand corner under the GIA logo. Below that number will be
the date of the document. Other places in which the report number will
appear will often be to the right of the centered "DIAMOND GRADING REPORT"
just below the addresses and the phone numbers of the lab. Phony GIA certificates
are known but THEY ARE QUITE RARE AND UNUSUAL. Very old certificates may
have an LA or NY in front of the number. This indicates whether the document
was created in the Los Angeles office or the New York office.
3.Shape and Cutting Style:
This will tell you the type of cut. Possibilities include round brilliant,
pear brilliant, oval brilliant, emerald cut, and heart brilliant. Two of
the most popular cuts today are the radiant and princess. The GIA refers
to these cuts as "cushion octagon modified brilliant" and "rectangular
modified brilliant" respectively.
4.Measurements:
Measurements are made in millimeters to the hundredth of a millimeter.
The measurements are taken 3 ways; length, width and depth. This is one
of the two most important items for making sure the diamond matches the
certificate. The chances of getting two diamonds that have the same measurements
to the hundredth of a millimeter for all three dimensions is astronomically
low. Couple this information with the plot of inclusions provided on the
document, and the matching of stone and certificate becomes easy.
5.Weight:
The weight of a diamond is expressed in carats. 144 carats equals one
troy ounce. A carat is divided into 100 points. Therefore a 25 point stone
is .25 carat. A 75 point stone is .75 carat, and so on. The heavier the
stone,
the rarer the stone. In a specific quality, a larger diamond will cost
more than a small one. Prices increase on a per carat basis tremendously
as the carat size increases up to five carats. Stones larger than 5 carats
increase on a per carat basis more slowly above five carats. In fine stones,
however, the per carat price is so high that the addition of one or more
carats over five can escalate the total price of the stone tremendously.
6.Proportions:
This section describes the proportions of various parts of the diamond
in relation to other parts of the diamond. The Depth % tells how
deep the stone is in relation to the diameter. In some cases, and depending
on the cut, a stone may be too deep or too shallow to bring out maximum
brilliance. The actual acceptable depth % varies from cut to cut so it
is important to talk to an expert about the particular diamond you are
considering. Round stones have much tighter acceptable standards than do
fancy shapes. The Table % is the percent that the flat top facet
called the table takes up against the diameter of the stone. Again, acceptable
table percentages vary according to the cut, but the round has the tightest
acceptable standards. The Girdle is the thin rim that separates the
top or crown of the stone from the pavilion or underside of the stone.
This rim may be unpolished or faceted. It may have a "natural" which is
a small portion of the outside of the rough diamond on it. It may be thin
to extremely thick. Thin to thick is usually acceptable. The Culet
is the little facet on the very tip on the bottom of the stone. Some stones
don't have a culet some have large ones (often on old cuts like Old European
or old mine cuts). Large culets that can be readily seen with the naked
eye are generally considered unacceptable.
7.Finish:
These two grades indicate the grade of the polish and the symmetry of
the stone. The polish of course is how well the stone is polished and a
main consideration in that grade is the absence of polishing marks - normally
seen under magnification. The symmetry indicates how well the facets in
the top of the stone line up with the bottom facets. In very fine stones,
it is preferred for both to be good, very good, or excellent. Fair is sometimes
acceptable in symmetry but very seldom acceptable in polish.
8.Clarity Grade:
The clarity grade will always be given. See our section on the basics
of diamond grading for more details.
9.Color Grade:
The color grade of the stone will always be given. See our section on
the basics of diamond grading for more details.
10.Fluorescence:
About one out of every ten diamonds glow in ultraviolet light. Most
glow blue, but other colors may occur including yellow, orange and green.
Blue fluorescence is usually a plus for white stones, so long as it is
not too strong. Yellow, orange, pink, and green are usually a detriment
for white diamonds, but a strong yellow fluorescence in a fancy yellow
diamond is a positive attribute. By and large, most fluorescence is just
another form of identification of the diamond and does not effect the value.
11.Comments:
This space is reserved for things that the laboratory wants you to know
but they do not fit into the format of the report. Most comments are minor
and do not impact the value of the stone.
12.The Plot:
The plot of the diamond shows both the significant internal inclusions
and the externally important items which are evident under 10 power. Again,
the plot is the most significant thing that will match the stone to the
document.
Home Page
| Why from Five Star | Why
GIA | Personal Info on Owner
| Refund Policy | Do's and Don'ts | Four C's | Anatomy
of GIA | Which Certificate | Current
Debates | In-Town or Out-of-Town | Ideal
Cuts really Ideal |
Round Inventory
| Fancy Inventory | This
Week's Special |
Email Us
Click here to return to home page
gipoco.com
is neither affiliated with the authors of this page or responsible
for its contents. This is a safe-cache copy of the original web site.
gipoco.com
is neither affiliated with the authors of this page nor responsible
for its contents. This is a safe-cache copy of the original web site.