The 4 C's of Diamond Buying

Color

Some consider this to be the most important factor when grading a diamond. Graded on a scale of colorless to fancy colors, lack of color in a diamond is not necessarily better, merely rarer. The grading scale goes from D, which is colorless, to Z, which is in the fancy color range.

D, E and F – Colorless
G, H, I and J – Near Colorless
K, L and M – Faint Yellow or Brown
Very Light Yellow or Brown
S through Z – Tinted Color

Clarity

A study of the internal and surface marks of a diamond yields its clarity grade. Graded on a scale from flawless to imperfect, with a 10x magnification used, the inclusions in a diamond may be other diamond crystals, small garnets, enclosed fractures or pockets, and other crystals which are common in the diamond. Inclusions are sometimes called "flaws," but nothing in nature is truly perfect and it is better to think of them as inclusions. Unless the diamond is graded in the I2 or I3 range, these inclusions rarely threaten the durability of a diamond and are rarely seen by the unaided eye. The grading scale, as used by the Gemological Institute of America (GIA) is as follows:

FL – Flawless
IF – Internally Flawless
VVS1 and VVS2 – Very very slightly included
VS1 and VS2 – Very slightly included
SI1 and SI2 – Slightly Included
I1, I2, and I3 – Included
P – Heavily Included or Pique

Cut

The study of a diamond's proportioning and finish yields its cut grade. Cutting can affect the following optical properties of the diamond:

Brilliance – The "brightness" of the stone; the reflections of white light within the stone.

Dispersion – The "fire" of the stone; the breaking up of the white light into its component spectral colors.

Scintillation – The "sparkle" of the stone; the momentary flashes of light from the facets of a gem caused by motion.

Luster – The "shine" of the stone; the quality and quantity of reflected light from a gem.

Carat Weight

Refers to the size of the stone. One carat equals 0.200 metric gram. If, and only if, other factors are equal, then the larger the stone the greater the value. Because of the first 3 C's, you can never say that just because one diamond is larger than another that it is more valuable. Diamonds are also measured in points, with one carat being equal to one hundred points. Usually, the higher the carat weight, the more you pay per carat, that is, two one–quarter carat diamonds will not cost the same as one half–carat stone of the same quality.