Diamond
Grading Diamond
Grading The following Quality Factors all affect the value of a diamond, also known as the "4 C's":
Color
Clarity
Cut
Carat Weight
Color is the most important factor. The Gemological Institute of America (G.I.A.) grading system is the world's most recognized system of evaluating a diamonds quality and value. Each grade describes a different aspect of the diamond and it is only the sum total of all these characteristics which will determine the overall value of the diamond. Diamonds are rated in colors of D through Z, as roughly shown below.
D-F are the finest & brightest
colorless diamonds, usually for the discriminating customer
who can afford the most beautiful and the rare.
G-H are very white & bright face-up
colorless diamonds that are not as expensive,
and when mounted in jewelry it is difficult to see the a
difference between these and the higher grades.
I-J are are not quite as bright or have
very slight hardly noticeable tint.
K-L have a slight tint even the average
person will begin to notice.
M or Lower the color will be noticed.
Clarity is
the next most important factor in determining a stone's value.
Clear, clean, transparent stones with no visible inclusions tend
to be the most valuable. Every natural stone will have some
inclusions that can be seen with strong magnification but if a
stone appears clean with the unaided eye it is referred to as
"eye clean".
The clarity scale ranges from F to I-3. This entire scale can be
divided in half, with diamonds that you can visually see the
imperfections to the unaided eye, and diamonds that require 10
power magnification to see the imperfections. This division is at
the I-1 clarity grade to the SI-2 clarity grade.
FL -
FLAWLESS describes
diamonds in which a gemologist under favorable lighting
conditions,
cannot see any inclusions at ten power magnification.
IF -
INTERNALLY FLAWLESS describes
diamonds which have no internal characteristics observable
under the the same conditions as (FL), but which have minor
surface blemishes that do not penetrate the stone.
VVS1 &
VVS2 - VERY, VERY SLIGHTLY INCLUDED describes diamonds that have very,
very small inclusions which are difficult for a gemologist to see
at 10x magnification.
VS1 &
VS2 - VERY SLIGHTLY INCLUDED describes stones with very small
inclusions which
can be difficult to observe with 10x magnification. Inclusions
are barely visible to the unaided eye,
except on larger stones or occasionally with Emerald Cut
diamonds.
SI1 &
SI2 - SLIGHTLY INCLUDED describes stones with small
inclusions which are usually
obvious when viewed with 10x magnification. Inclusions are
difficult to see with the unaided eye,
except on larger stones or occasionally with Emerald Cut
diamonds.
I1, I2,
& I3 - IMPERFECT describes
stones with medium to large inclusions (Piques) which are
usually obvious to a gemologist with the unaided eye. An I1 may
have an inclusion located to the side
while an I2 will have it centerally located or numerous
inclusions.
Cut is
sometimes overlooked as an important factor in determining a
diamond's value, but it is usually
critical in determining the overall look and beauty. A stone that
is cut too deep will often darken out, while
a shallow cut will "window" and appear lifeless in the
middle. A well cut gem will reflect light throughout
the stone and appear brilliant. Never underestimate the value of
cutting because even ordinary rough
can be crafted into extraordinarily beautiful gemstones by a
masterful cutter.
The Cut determines how much light which enters the diamond from
above, then how much light
will be reflected and refracted back out of the gem to the eye of
the observer. In other words how pretty
the diamond can be is decided by the cut. For the consumer it is
fairly easy to determine in general terms
if a round brilliant cut diamond is well cut or proportioned.
Generally if the size to weight ratio are cut
correctly the entire bottom side of the diamond is turned into a
mirror. If the cut has been poorly
done even the highest quality grade diamond will look lifeless.
Carat weight, means weight of the stone (1 carat = 1/5 of a
gram). The diamond weight is a
very important factor to its cost. The term "carat "
originated from the seeds of the carob tree.
These carob seeds are extremely uniform in weight which made them
the ideal weight unit
for the ancient gem traders. This weight (one carob seed) was
later standardized to be 1 carat, or
1/5th of a gram, hence a five carat diamond equals 1 gram. The
one carat weight is then broken
down into 100 equal parts called "points"; 75 points
equal 3/4 of a carat, 50 points equal 1/2 of a
carat, etc. It is important to understand that the weight of a
diamond and its physical size
are two different things.
