The second C used in rating diamonds is color. Diamonds come in literally
every color in the rainbow and while a few specialty colored diamonds are
extremely valuable because of their deep hues and unique color characteristics,
these are the exceptions rather than the rule. In general, the closer a stone
is to possessing no color, that is, to being colorless, the more the stone is
worth.
In order to establish the transparency or lack of color in a diamond, the
loose stone is placed on a pure white background under a white light. There
are special lights sold with adjusted color temperatures for this viewing or
some people prefer to use the soft north sunlight when trying to view the
color of a diamond.
In color rating as in clarity rating, the dazzling brilliance and fire of a
diamond are the viewer’s natural enemy. They will confuse the eye and care
must be exercised to not become jaded or tricked, but rather to view each
characteristic individually and in comparison to other stones or photographs
of stones.
The most accepted color grading system is that again of the GIA. Their system
is judged by using a series of master stones sold by the GIA or their
representatives that establish hues and tints and can be laid side by side
with the stone in question in order to view how “white” the stone really is.
If at all possible, it is certainly worth one’s time to visit a large gem
dealer with the intent or apparent intent of purchasing a goodsized stone and
ask to see a master set and become used to judging the color on several stones
until you have a feel for the concept of whiteness, transparency and hues.
Technology has now produced a practical and inexpensive (comparatively) method
of possessing your own diamond master stones. These stones are available in all
colors D through Z on the GIA scale and are excellent to have on hand to
compare with any other stone you may be considering purchasing in order to
rate the new stone. These stones are color correct because they’re created to
be exactly the color they’re supposed to be.
How can this be cheap? The stones are not diamonds. They’re CZ’s, cubic
zirconia. These CZ stones look like diamonds, act like diamonds, smell like
diamonds and can be matched to a real diamond in order to compare colors with
an extreme degree of accuracy.
There’s also a device known as a color meter which electronically measures the
color or lack of color in a stone. This meter is quite accurate although
fairly hard to come by unless one is a member of the Gemological Institute of
America.
The GIA color rating system has been established using alphabetical
nomenclature. The stones are rated from pure (totally colorless) down through
a sliding scale to yellow, which is the least valuable stone. The GIA color
rating system starts with the letter D and progresses through the alphabet as
shown below to Z, which would be very yellow.
A B C D E F ) Colorless
G H I J ) Near Colorless
K L ) Faint
M ) Yellow-White
N O ) Very Light Yellow
P ) Light Yellow
Q ) Yellow
R S T U ) Light
V ) Yellow to Fancy
W ) Fancy
X Y Z ) Yellow
After the letter Z, indicators are used to suggest the stone is more valuable
because of its hue; i.e., a “fancy” color. As you can see from the above chart,
D, E and F stones are considered completely colorless. G, H, I and J are near
colorless stones and take a lot of practice for the amateur to see any color
at all, while after J the stones begin to pick up a small tint of yellow that
is noticeable to practiced gemologists.
To correctly grade a gemstone, the stone must be loose, not in a setting,
should be on a perfectly white background, should have a white gem quality
temperature light and should be viewed from the rear of the stone. In other
words, the stone should be upside down Iying on its table. It is also
extremely helpful to have stones of known color grades nearby for active
comparison.
Never attempt to judge the color of a diamond when it is set in any kind of
setting, be it earring, ring, or whatever as it is strictly impossible to
judge the color of a mounted stone that is taking on hues and tints from the
mounting itself.
Color is a very important consideration in choosing investment quality
diamonds and, in fact, the differences in large sizes such as one carat and
over from a D to an E color (again these are the top rated stones and are both
considered colorless to the naked eye) can be double the price between these
two grades.
