The 4C's are used throughout the world to classify the rarity of diamonds. Diamonds with the combination of the highest 4C ratings are more rare and consequently, more expensive.

Light is the element that ignites a diamond's brilliance and fire. Its interplay with each of the 4C's will help explain why one diamond can appear even more beautiful than another. The good news is that you don't need to buy the rarest diamond to find one whose beauty speaks to you.

CUT

Cut is the only one of the 4C's that is influenced by humans. The rest are created as naturally as diamonds from the earth. Cut refers to the angle and proportion a skilled craftsman creates in transforming a rough diamond into a polished diamond. Based on scientific formulas there are 3 types of diamonds:

Well Cut / Ideal Cut : A well cut diamond will internally reflect light from one mirror like facet to another and disperse and reflect it through the top of the stone. This results in the display of brilliance and fire. Shallow Cut : Light is lost out the bottom causing the diamond to lose brilliance. Deep Cut : Light escapes out the sides causing the diamond to appear dark and dull.

Diamond cutting requires great skill and training. The cutter must polish tiny surfaces known as facets onto the rough diamond. This process is what creates the crown, culet, table, girdle, and pavilion of the diamond.

Cut also refers to the shape of the diamond – round, marquise, pear, princess or heart for example.

COLOR

Diamonds range in color from icy whites to warm summer whites. Diamonds are graded on a color scale established by the Gemological Institute of America (GIA), which ranges from D (colorless) to Z.

Color differences are very subtle and it is very difficult to see the difference between, say, an E and a F. Therefore the colors are graded under controlled lighting conditions and are compared to a master set for accuracy. Truly colorless stones, graded D, treasured for their rarity are highest on the Diamond Quality Pyramid

Diamonds are graded in the following manner :

D E F : Colorless Diamonds. The highest color grade and high quality diamonds, which is extremely rare. An expert gemologist can only detect minute traces of color.
G-H-I-J : Near colorless. Color noticeable when compared to diamonds of better grades, but these grades offer excellent value.
K-L-M : Faint yellow colored diamonds.
N-O-P-Q-R : Very light yellow colored diamonds.
S-T-U-V-W-X-Y-Z-Z+ : Light yellow or yellow colored diamonds.

What color grade is best?

• For the purist, look for a colorless diamond with a grade of D-F and a fluorescence rating of faint, inert, none, or negligible.
• For an excellent value in a diamond with no noticeable color to the unaided eye, look for a near-colorless grade of G-I , and a fluorescence grade of medium or strong blue.
• Or, if you'd rather not compromise on color but would like to stay on budget, choose a diamond with a good cut, SI1–SI2 clarity, and consider going with a strong fluorescence. It will still be beautiful to the unaided eye and you may prefer the unique effect of a strong fluorescence.

CARAT

Refers to the weight of a diamond.

The term carat is derived from the word carob. Carob seeds are surprisingly similar in weight to one another; therefore they were used in ancient civilization as a tool to measure the weight of the diamond. One carob equaled 1-carat weight. Carat is often confused with size even though it is actually a measure of weight. One carat is equivalent to 200 milligrams. It can also be divided into 100 “points”. A 0.75-carat weight diamond is the same as a 75-points or ¾ carat diamond

A 1-carat diamond will cost much more than twice as much as the cost of a ½ carat diamond, assuming cut, clarity and color remain constant. Cut and mounting can make a diamond appear larger (or smaller) than its actual weight.

CLARITY

Refers to the presence of inclusion in a diamond.

When light enters a diamond it is reflected in and refracted out. If there is anything disrupting the flow of light in a diamond such as an inclusion, a proportion of light will be lost. As a result, brilliance could be diminished. The number of inclusions can determine the degree of brilliance lost.

Inclusions are sometimes referred to as “nature's fingerprints”, and are not visible to a naked eye unless magnified. Inclusions are ranked on a scale of perfection, known as clarity, which was established by GIA. The clarity scale from F (Flawless) to included (I), is based on the visibility on inclusions are a magnification of 10x.

The position of inclusion affects the value of a diamond. There are very few flawless diamonds found in nature, thus these diamonds are much more valuable.

VVS1 VVS2 VS1 VS2 SI1 SI2 SI3 I1 I2 I3

The number represents levels within each grade. The 1s will be cleaner (have fewer or smaller inclusions) than the 2s. This allows for more specific grading categories.

The position of diamond may affect the value of the diamond. One many not notice a significant difference between VS1 and VS2. However one should consider – number, size, brightness, nature and position of inclusion.

Sometimes inclusions can be hidden by a mounting, thus having little effect on the beauty of a diamond. An inclusion in the middle or top of a diamond could impact the dispersion of light, sometimes making the diamond less brilliant.

The greater a diamond's clarity, the more brilliant, valuable and rare it is – and the higher it is on the Diamond Grading Pyramid