It’s all about the Cs when it comes to buying a diamond: Color, Clarity, Cut and Carat.

According to the Gemological Institute of America (GIA), in independent, non-profit organization, diamond professionals rely on these four qualities to determine the value of the diamonds they sell.

Color.

A truly colorless diamond is quite rare, according to the GIA, so therefore, the less color in the stone, the higher its value. The truth is, however, that most diamonds are slightly tinged with yellow or brown. If so, they fall into the “normal” color range. The GIA’s color grading system starts with a “D” rating for colorless, and runs through Z. Along the way through the alphabet, diamonds can be classified as “near colorless,” “faint,” “very light” and “light.” In this D-Z color range, the D-rated diamond will always be more valuable than others, when all factors, such as clarity, carat weight and cut are equal.

Diamonds classified outside this color range are called “fancy colors,” and can come in a variety of colors, including pink and blue.

Clarity.

Clarity is also an important factor in determining a diamond’s value. Even after they have been cut and polished, blemishes may still remain. These blemishes, from inclusions and surface irregularities, are also rated on a Clarity Scale. Blemishes come from scratches and nicks on the diamond’s surface, while an inclusion can be a mineral crystal or other imperfection that became trapped in the diamond during formation. Gemologists look for these blemishes to help them separate a true diamond from a lab-created stone, and help identify individual stones, because no two are alike.

The GIA Clarity Scale offers six classifications, varying from “Flawless” for a stone with no inclusion or blemish at 10 times magnification, to “Included” for a stone that contains inclusions that are visible at 10 times magnification and may also affect a stone’s brilliance.

Cut.

A diamond’s shape is considered to be important because it also includes its proportion, symmetry and polish. A diamond with a good cut, or “make,” will be bright, fiery, and sparkly in the light.

The three major parts of a diamond, from top to bottom, are the crown, the girdle and the pavilion. The distance between the crown and the very bottom of the diamond - also called the culet - and the cuts that have been made in between them will determine how light flows through the stone. A diamond with a cut that is too shallow or wide will let light escape and will be less brilliant.

Carat Weight.

This is the basic unit measurement of a diamond. Diamonds are weighed to a thousandth of a carat (0.001) and then rounded up to the next hundredth, or point, according to the GIA. Visually, there is no difference between a diamond that weighs 0.99 ct., and one that weighs a full carat, but the price difference can be significant. This is particularly true if the diamond scores well in cut, color and clarity.

Large diamonds are rarer than small diamonds, and the scarcer it is, the more valuable it is expected to be.

Finally, the GIA asserts, all the Cs matter when it comes to buying a diamond, and no one element is more important than the other. They will all be factored together when it comes to determining the true value of a diamond.

- For more information about diamonds, contact Demares Jewelers at (707) 552-2000.

DeMares Jewelers

Price and size are not always the determining factor when selecting a diamond. When shopping, consider all of the following:

COLOR Most diamonds have some yellow or brown tinge. The less color in the stone, the higher the value.

CLARITY The fewer the scratches or nicks on the diamond’s surface, or blemishes inside the diamond itself, the more valuable the stone.

CUT The shape, proportion, symmetry and polish of a diamond will determine how it sparkles.

CARAT The weight of the diamond is measured in “carats”. The higher the carat, generally the higher the value, if all other factors are also considered high.