A polished diamond’s cut is divided into
proportion and finish.
A diamond’s proportions are its angles
and relative measurements and the relationships between
them. The basic choices a cutter makes when fashioning a
diamond include the size of the table, the crown and
pavilion angles and girdle thickness.
Other factors indicate the care the
polisher used when finishing it. These include the symmetry
of the facets and their relationship to one another as well
as the fineness of the polish. These elements all contribute
to a diamond overall appearance.
Proportions are the size and
angle relationships between the facets and different parts
of the stone. Proportion affect how a diamond "scintillates"
or shines because it affects how light is reflected and
refracted inside the stone, which is what causes diamonds to
Each part of a diamond makes
its own contribution to the diamond’s appearance. The table
facet gathers light from above and either reflects it back
or directs it into the diamond’s interior. The crown facets
gather and disperse light to create fire. The pavilion
facets take the light that comes in through the crown and
direct it back out to the viewer’s eye. The girdle makes an
important contribution of its own by providing a location
for the diamond to be secured into a setting.
Those are the ranges for a
diamond with excellent proportions:
All of a diamonds
proportions will be measured and compared with
industry-consented benchmarks and then be graded
individually according to how much a stone’s proportions
measurements vary from the agreed standards. The lowest cut
grade will set the grade. The cut grade will be graded on a
scale from excellent to poor.
The Cut grade is an important parameter in the round
brilliant diamond grading report, but it isn’t used in the
other shapes grading reports. The fancy diamond grading
reports don’t a have a cut grade.
Finish is made up of polish and
Polish is the overall condition
of the diamond’s facet surfaces it describes how well light
enters and exits the facets of the diamond. Polish can be a
result of the finishing process or be affected by blemishes
created after cutting. There are certain polish
characteristics frequently seen on diamonds. There might be
traces left by the polishing wheel or from polishing too
fast or against a polishing direction.
Polish is graded on a scale
from excellent to poor.
Excellent: Ranges from no polish features to a few
minute features that can be located with difficulty under 10X magnification.
Very Good: A few minor features when viewed under 10X
Good: Areas of noticeable features when viewed under
10X magnification. The Might slightly affect luster when seen by the
Fair: Areas of obvious, heavy features when viewed
under 10X magnification. Affects luster when seen by the unaided eye.
Poor: Areas of prominent, heavy features when viewed
under 10X magnification. Significantly affects luster when
seen by the unaided eye.
Symmetry refers to the evenness
of a diamond’s outline, the exactness of the shape and
placement of the facets. Most diamonds have a least a few
symmetry variations, but they typically have little effect
on appearance, at least to the unaided eye.
Symmetry is graded on a scale
from excellent to poor.
Excellent: Ranges from no symmetry variations to minute
variations that can be viewed with difficulty under 10X magnification.
Very Good: Minor symmetry variations seen under 10X
Good: Noticeable symmetry variations seen under 10X
magnification. The diamond’s overall
appearance might be slightly affected when viewed with the
Fair: Obvious symmetry variations seen under 10X
magnification. The diamond’s overall appearance is often
affected when viewed with the unaided eye.
Poor: Prominent symmetry variations seen under 10X
magnification. The diamond’s overall appearance is
significantly affected when viewed with the unaided eye.
The modern round brilliant has
a round girdle outline, symmetrically placed triangular and
kite-shaped facets, a table that’s larger than 50 percent of
the girdle diameter, and a small culet or none at all.
More than 500 years of
experimentation led to the introduction of the modern round
brilliant cut in the early 1900’s. Its intricate proportions
showcase a diamond’s brilliance and fire with dazzling
effectiveness. The round brilliant still remains the
dominant diamond cut in the marketplace today.
The other diamond cuts are
called fancy shapes.
Here are a few example:
Many diamonds emit light, or glow, when they’re exposed to
ultra violet (UV) radiation.
This is called fluorescence and its caused by an interaction
between the UV radiation’s energy and the diamond’s atoms. A
diamond’s degree of fluorescence doesn’t necessarily affect
its appearance in most lighting situations, it will only be
noticeable under the concentrated longwave ultraviolet
radiation of a UV lamp. About one-third of gem-quality
will emit some degree of fluorescence.
On the laboratory diamond grading reports, the fluorescence
entry is a description, not a grade. The terms for
describing fluorescence are NONE, FAINT, MEDIUM, STRONG,
VERY STRONG. Most of the diamonds that fluoresce do so in
varying strengths of blue, however, diamonds can fluoresce
in almost any color.
Leiser & Co only sells diamonds graded & certified by the
most reputable gemological laboratories, the GIA, HRD, IGI
laboratories grade hundreds of thousands of diamonds a year.
That much repetition makes the grades on the diamond reports
highly reliable and consistent. Another factor that
contributes to the accuracy of the grades is that several
graders examine each diamond. A quality report from any of
those laboratories allows anybody to choose a diamond
without seeing it.
A report can also
work the other way: you can check a diamond that’s
accompanied by a quality report to make sure it matches its
description. This protects you against switched stones.
1931, the Gemological Institute of America (GIA) is the
world’s foremost authority on diamonds, colored stones, and
GIA exists to protect all purchasers of gemstones, by
needed to accurately and objectively determine gemstone
The Hoge Raad
voor Diamant (HRD)’s primary shareholder is the Antwerp
World Diamond Centre (AWDC). The AWDC is a private
foundation established in 1973 as (HRD) or Diamond High
Council and represents the Belgian diamond industry.
Over more than 30 years, HRD
Antwerp has gained the diamond industry’s confidence by
offering high-quality solutions, a highly reputable lab, as
well as massive in-house expertise and experience.
HRD Antwerp offers a wide range
of services and equipment geared for the use of diamond and
jewellery professionals as well as for the diamond and
jewellery buying public.
International Gemological Institute (IGI).,
was founded in 1975 and along with its sister laboratories
is one of the leading gemological institutions worldwide.
Established in Antwerp, New York, Hong Kong, Mumbai, Bangkok, Tokyo, Dubai, Toronto, Los Angeles, Tel Aviv and Cavalese, IGI is the world's largest independent gem certification and appraisal institute and is renowned for its quality services, extensive experience and know-how. Presently, a staff of more than 500 professionals dedicated to a standard of excellence second to none and IGI issues more than one