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| Gemstone
Buyer's Guide: Certified
Diamond Buyer's Guide |
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Certified
Diamond Buyer's Guide
With statements of mathematical
percentages and proportions, fluorescence and symmetry, diamond
certificates can appear overwhelming to those unfamiliar with
their concepts and terminology. The Hannoush Jewelers guide to
certified diamonds will give you a thorough understanding of
their terms, which will allow you to shop with total confidence!
The inherent value of a diamond certificate is that it
is both an independent and absolute guarantee of a diamond’s quality – meaning
you have total 100% peace of mind when spending thousands
of dollars. This peace of mind
derives from the fact that a diamond certificate is an extremely precise
communication tool for all the complex information needed to accurately
evaluate a large quality diamond. |
| The
Inherent Value of a Diamond Certificate |
Not
included in the somewhat clichéd 4C’s information set, is the
more explicit information that can make a large difference to
the price of a diamond. On top of the 4C’s, a diamond’s depth,
table, girdle, culet, polish, symmetry and fluorescence must
also be considered.
While certification is not always necessary, especially
on diamonds under 0.75 Carats or when you’re looking
to pay well below market prices, a diamond certificate
allows buyers and sellers, in totally different
parts of the
world, to accurately exchange precise information regarding these critical
factors.
Unlike colored gemstones, diamonds are cut, shaped
and proportioned to remarkably uniform ideals.
In 1919, Marcel Tolkowsky published his theories
regarding ideal diamond proportions. Tolkwosky’s proportions, which resulted
in an optimum balance of brilliance and fire, have become the “industry
standard” for larger diamonds. Today, larger diamonds (i.e. over 0.75 Carats)
that fail to conform to Tolkwosky’s prescribed proportions can be comparatively
less beautiful and are consequently less valued.
Depth Affects Beauty
Tolkwosky’s theories state that ideally a diamond’s
depth should proportionately fall between 58% to
62% of its width or diameter. Measured from the
culet
to the crown, diamonds that possess these ideal proportions reflect light
with the highest efficiency, resulting in the greatest beauty possible.
Diamonds that fail to conform to these ideals start
to exhibit imperfections in their beauty. Diamonds
that are cut with less than a 57% depth often
possess “fish-eyes” – whereby an undesirable dark ring, that is actually
a reflection of the diamonds girdle, is seen inside the pavilion. Conversely,
those diamonds that possess a depth greater than 65% display what is sometimes
called a “nail head” – whereby a dark reflection from the table is seen
inside the pavilion.
Depth is always expressed as a percentage on a diamond certificate.
Table
Sizes Affect The Brilliance Versus Fire Relationship
Often under appreciated, is the ability of the
size of a diamond's table to affect the relational
balance of brilliance and fire. The larger the
table area that covers the crown of the diamond, the greater the amount
of uninterrupted brilliance seen – but at the expense of the multicolored “fire” effect
for which diamonds are so synonymous.
Conversely, the smaller the table area is, the
larger the area of the angular crown. Large angular
crown areas result in more refracted light, meaning
we see more color and “fire”.
The left hand diamond possesses the most fire, the right hand diamond
possesses the most brilliance. As we move from left to right we see
brilliance increase, but at the expense of fiery twinkling color.
Over the past few years there has been a trend
for smaller tables in order to give diamonds more
fire. Currently, most diamond factories aim for
about
53% - 60% of the crown of a round brilliant cut diamond being covered by
the table. The table size is always expressed as a percentage on a diamond
certificate, however please bear in mind there is no “optimum” percentage
as a perfect balance of brilliance and fire is subjective and is very much
down to personal taste.
Girdles – Not
Too Thick, Not Too Thin
The girdle is an often un-faceted band around the outer most section of
a diamond or gemstone, separating the crown from the pavilion. While sometimes
polished, and stated so on a diamond certificate, the merits of faceted
girdles are subjective and is again, very much down to personal taste.
More important is the thickness of a diamond’s girdle – the
ideal is neither too thick nor too thin. Girdles
that are very thin and knife-edge like
afford a diamond little protection against knocks and abrasion. Conversely,
girdles that are overly thick add weight but not size, making the diamond
look too small for the stated carat weight.
Common grades for girdles in diamond certificate
are “Extremely Thin”, “Very
Thin”, “Thin”, “Medium”, “Slightly Thick”, “Thick”, “Very Thick” and “Extremely
Thick”. Girdles of an inconstant thickness are expressed in a range such
as “Medium To Slightly Thick”. Girdles that change in thickness around
their circumference are viewed as a minor and somewhat trivial flaw.
Present At The Bottom Of this Diamond Is A Faceted Culet To Protect Against
Abrasion.
To Culet
Or Not To Culet? 
The culet is the sometimes-present facet on the
bottom of a diamond’s pavilion.
Often seen as a “keel” on oval and emerald cut diamonds, culets protect
the sharp and narrow termination of a diamond’s pavilion from damage and
abrasion.
In today’s diamond markets, culets have become less common as their presence
can slightly detract from a diamond’s carat weight. Overly large culets
are undesirable, as they tend to open up a “window” on an otherwise perfectly
brilliant gem.
Polish – The
Smoother The Better
The polish condition of a diamond should be good.
Ranked on a diamond certificate as “Very Good”, “Good”, “Fair” and “Poor”,
the quality of polish is affected by the presence
of extra facets, naturals (i.e. remains of the
original
unpolished crystal surface), polishing lines, abrasions, surface pits and
burn marks from polishing.
Symmetry – Matching
Opposites
The cut of a diamond should exhibit good symmetry. Ideally, crown facets
should be aligned straight in relation to facets on the pavilion, the girdle
and to each other. Furthermore, facets should not be misshapen and the
table should ideally be a regular octagon.
These ideals pale into insignificance when compared to serious symmetrical
faults that can downgrade symmetry on a certificate. Serious faults include
off-round girdles, wavy girdles, off-centre tables and off centre culets.
Grades for symmetry include “Ideal”, “Excellent”, “Very Good”, “Good”, “Fair” and “Poor”.
Fluorescence – Who
Wants A Blue-White Diamond?
Have you ever heard of a “blue-white” diamond? They are diamonds that possess
blue-white fluorescence. Once considered the crème de la crème, styles
have now changed, with one of the prevalent beliefs of the diamond trade
being that diamonds with fluorescence are less desirable.
Despite this modernist view on this blue-white effect, fluorescence can
actually greatly benefit a diamond. Diamonds with tinted color grades of
H to M actually benefit from a moderate amount of fluorescence, as the
effect makes the diamond look whiter.
Some people actively admire this fluorescence and appreciate its subtle
blue-white effect. Whatever your opinion on the merits of blue-white fluorescence,
many diamonds possess this property and they often represent exceptionally
good value.
If you take all of the above into account when
reviewing a diamond certificate, you’ll be well on your way to buying quality diamonds with absolute confidence.
However, please remember that certification is not always necessary, especially
on diamonds under 0.75 Carats or when you’re looking to pay well below
market prices. |
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