Of the four Cs, cut is perhaps the most important
factor affecting a diamond's overall quality and beauty. A diamond's
brightness, or its brilliance, is determined by how much light is
reflected back to your eyes. Light enters the stone through the
crown, which is the portion of the diamond above the girdle. The crown
is made up of the table, which is the large flat facet on top of the
diamond, and many crown facets. It then travels to the pavilion, or
body, of the stone, where it is reflected from one side to the other and then
back through the top and to an observer's eye.
A well cut, well
proportioned stone evenly reflects and refracts light within the stone, thereby
producing an eye-catching, fiery spectrum of color. A poorly cut
diamond, on the other hand, allows more light to pass through or "leak" from the
sides of the stone, which results in a lifeless appearance with reduced
The science behind
diamond cutting is more or less an exercise in proportion. Changing the
proportion of a diamond's depth and width is done in order to maximize the
stone's brilliance. If the cut adheres to certain "ideal" proportions, the
results can be spectacular. If poorly cut, the results can be so bad as to
cause structural instability, which makes the stone susceptible to breaking.
Because cut is so important, gemologists have developed grading methods to
assist consumers in determining a diamond's cut. In general, they
are: Ideal, Excellent, Very Good, Good and Fair.
The ideal proportions
shown below are known as the Tolkowsky Theoretical Brilliant cut.
In 1919, Marcel Tolkowsky published a paper detailing ideal proportions for a
round brilliant diamond. Modern cutters offer a wide range of opinions on
the "ideal" cut, but Tolkowsky's findings are mathematically indisputable and
remain the basis for these modern ideal proportions.
The measurement and comparison of diamond color
ranges from colorless to slightly tinted. However, discerning the subtle
differences between sequential color grades can be almost impossible with the
naked eye. For this reason, a letter scale, such as the GIA professional
color scale which ranges from D to Z, was created to assist in distinguishing a
diamond's color grade. Diamonds that are in the "D-F" range are
considered colorless. These diamonds are rarer and more
expensive. Diamonds in the "G-I" range appear completely
white to most observers and for this reason can be a better value than colorless
diamonds. Color grades beyond "J" exhibit a yellowish or brownish tint,
which is increasingly discernable by the untrained eye as you approach the
extreme end of the spectrum.
A carat is a unit of measure for diamonds,
where one carat equals 100 points, or 0.2 grams. This measurement is
referred to as the carat weight and is used to determine a diamond's size.
Larger diamonds are more rare and therefore more highly valued. In
addition, larger diamonds make it easier to see the effects of other key
characteristics, such as cut and color. Depending on the
significance of these other characteristics, diamonds of a similar size (carat
weight) may differ dramatically in price.
Clarity is most often mistaken as being the
factor that determines a diamond's sparkle and brilliance. This is not
true. Clarity describes the presence of imperfections both on and within a
diamond. Most imperfections are microscopic flaws, or "inclusions," formed
inside the diamond during the formation process known as crystallization.
Other flaws, however, appear on the surface of a diamond and may have appeared
during the cutting process.
Essentially, the clarity
grade describes the flawlessness of a diamond; the fewer the imperfections,
the higher the clarity grading. Naturally, these imperfections have an
impact on the value of a diamond, particularly those that may be viewed by the
naked eye. In order to find and plot a stone's flaws, gemologists use at
least 10x loupe magnification when grading for clarity. Clarity grades
range from Flawless, which are diamonds that reveal no imperfection even under
10x magnification, to Imperfect 3, which are stones with distinct blemishes
visible to the naked eye. See the chart below for a description of each
FL / IF
Flawless or Internally
VVS1 / VVS2
Very, Very Small Inclusions.
Requires 60X magnification to clearly see inclusions.
VS1 / VS2
Very Small Inclusions. Requires
30X magnification to clearly see inclusions. A good choice for those
wishing to balance quality and affordability.
SI1 / SI2
Small Inclusions. Typically
requires 10X magnification to clearly see inclusions. In larger
carat weights, SI diamonds sometimes reveal their inclusions to the naked
eye. Nonetheless, as long as you are careful to consider each stone
individually, you can often find the best value in an SI1 or SI2
Inclusions. Often a popular choice for earrings or pendants, as
these items are generally scrutinized less than diamond rings. Also
a popular choice for those shopping on a budget.
I2 / I3
Imperfect. Not recommended
for any practical jewelry