Color is an important factor to beauty, rarity, and value because it is something a consumer can see without the aid of equipment. Diamonds come in all colors imaginable. They become colored when elements such as nitrogen (yellow) and boron (blue) mix with carbon when the diamond is formed. The most rare diamond colors are red, pink, green, and blue. Diamonds that display enough of a hue, or nuance of color to be desirable, are called fancy-colored diamonds.
The diamonds that most of us will buy, however, are essentially white or yellow in color. Whiter diamonds are more expensive because they allow more light pass through it, therefore more sparkly and bright. In grading a diamond, the highest grade is colorless, while the lower grades will carry a yellow tinge. One interesting thing about color is that some people are more sensitive to the yellowness in the diamonds. So even though you can't see the yellow tinge in stone with naked eyes, your fiancée might be able to see it!
The grades of color as defined by the two most common certificate labs:
| AGS |
0 |
0.5 |
1.0 |
1.5 |
2.0 |
2.5 |
3.0 |
3.5 |
4.0 |
4.5 |
| GIA |
D |
E |
F |
G |
H |
I |
J |
K |
L |
M |
| AGS |
5.0 |
5.5 |
6.0 |
6.5 |
7.0 |
7.5 |
8.0 |
8.5 |
9.0 |
9.5 |
10.0 |
| GIA |
N |
O |
P |
Q |
R |
S |
T |
U |
V |
W |
X,Y,Z |
In GIA-speak, D to F are "colorless", G to I "nearly colorless", J to L "Slightly Yellow", M to O "Light Yellow", and so on.
The shape of a diamond could affect your choice for the color grade too. An emerald shaped diamond has a larger table (i.e. the top surface), reveals the body color and clarity much more than other shapes. A slight trace of yellow that may not be visible in another shape might be easily discerned here.
Fluorescence
The reaction of a diamond towards UV (ultraviolet) lights is called fluorescence. A diamond with fluorescence will have a blue hue under UV lights and might be cloudy in sunlight, depending on its color grade. Diamonds with fluorescence are lower priced than those without. On the other hand, according to a GIA study, fluorescent diamonds are preferred by the observers over non-fluorescent diamonds, because there is usually some UV under many viewing conditions (e.g. sunlight, or fluorescent tubes in the office), and the blue hue makes the diamond look more colorless.
There are some diamonds which fluoresces with a yellow, orange or even pink hue, but they are rare.
The bottom line is that slight fluorescence probably doesn't hurt and might actually save you a few bucks, but too much of it is definitely not good.
More about Colored Diamonds
Unusual diamond colors can be produced artificially through treatment, or so-called "enhancement". Any consumer interested in a fancy-colored diamond, should consider asking for an origin of color report issued by the GIA. They are usually much more expensive, so if you are ever offered to buy a red or blue diamond at a price comparable to normal diamonds, beware that it's too good to be true.
