Color in a diamond refers to the body tone of the diamond. Our diamonds are graded on a scale of D through Z following the grading system used by the Gemological Institute of America (GIA).  The highest grade, D, is the purest white color. Each subsequent letter corresponds to a slightly darker shade with Z being the lowest color grade on the scale. The whitest diamond possible would be a pure carbon crystal with a perfect crystal structure, and free of all other elements.  In reality, this does not exist.  The most common element mixing in the carbon structure of a diamond is nitrogen, which can give the diamond a yellow tint.

A truly colorless diamond is extremely rare.  Most diamonds possess varying degrees of color.  Small, subtle differences in color can make a substantial difference in a diamond's value.

At Since1910, we only carry diamonds up to J.  A J rating marks the low end of the white scale, and in our opinion is the minimum color that should be considered for a fine piece of jewelry.  The exception to this would be when you go beyond Z in color into what is called fancy colored diamonds.  These can be found in varying degrees of intensity and in almost all colors.  They can be priced from thousands per carat to over one million per carat depending on their rarity.

Many factors must be considered when deciding on a color, as you want a diamond that is going to look as white as possible while keeping within the parameters of your budget.

1. If a diamond is well cut, the diamond's refraction and dispersion often will disguise certain degrees of coloration to the point where it may make a darker diamond appear whiter when looked at with the naked eye (without magnification).  The GIA, when instructing students taking their graduate gemologist course, states that when a diamond is being graded for color and it is set in a mounting, there is a degree of error of up to 3 color grades. This demonstrates how fine a line there is between grades.  When the GIA issues a certificate, it is for a diamond that has been graded unmounted and viewed face down in a laboratory environment where natural daylight is simulated.  Once put in a setting and viewed face up in various lighting environments, differences become much more difficult to discern.
2. The size of the diamond can also affect the appearance of its color.  The larger the diamond, the more apparent the color of the diamond will be.  For diamonds under 1/2 carat in size, it is difficult for anyone, except a trained gemologist viewing the diamonds under magnification, to see the difference in the color of two otherwise similar diamonds that may be two or three grades apart.  In larger diamonds it does become easier; however, while there is a very fine difference between one grade to the next, the price differential can be significant.  Again, it often takes a trained gemologist to differentiate between the two.  If a larger diamond is a priority, you should consider sacrificing slightly on the color.
3. The shape of the diamond can also affect its color.  Most notably, would be that of the emerald and asscher cuts, which are step cut diamonds that do not display the brilliance of some of the other cuts.  The center of these diamonds can display a window effect where some of the color in the diamond can appear washed out and make it appear whiter then its actual color grade would indicate.  The shallower the cut of the diamond, the more evident this would be.

Below is a chart showing how the price of an excellent cut one carat diamond of VS2 clarity (very small inclusions under ten power magnification) is affected by color.

Fluoresence

One additional factor in grading the color of a diamond is fluorescence.  This is the property of a diamond to fluoresce under the long-wave ultraviolet spectrum of light.  Approximately 10% of all diamonds exhibit this quality.  Years ago, such diamonds were referred to as blue white diamonds.  Today, fluorescence on a gem grading certificate is divided into five different categories: none, faint, medium, strong, and very strong.  Most diamonds that do fluoresce, fluoresce a blue color; however, yellow and other colors are possible. 

Fluorescence can be both a negative and a positive.  In the strong and very strong range, it can, in some cases, make a diamond appear oily or cloudy--greatly reducing the desirability and value of the diamond.  However, diamonds of I color and lower can actually look whiter with some fluorescence; thus, enhancing their value.  Better quality diamonds with fluorescence generally sell at a discount to similar ones without.  The usual reason is not that it is less beautiful, but that the general public is under the opinion that fluorescence is a negative.  It is easier for a jeweler to sell a diamond without fluorescence  than it is to try and explain it.