Diamond
About Diamonds and the 4 C's

Carat

The size of a diamond has the biggest impact on its price. The metric carat, which equals 0.20 gram, is the standard unit of weight for diamonds and most other gems. If other factors are equal, the more a stone weighs, the more valuable it will be. Gemological laboratories measure carat weight when the diamond is loose (unmounted). While it is possible to estimate the weight of a mounted diamond, the lab uses ultrasensitive scales to achieve an exact weight, measured 3 decimal places, although the third decimal place is not usually mentioned at the retail level.

Here are several ways to express 1 carat:

Prices of diamonds are expressed in the trade as a price per carat. When we say that the Carat Weight has the biggest impact on the price of a diamond, not only is that true for the overall price of the stone, it is also true for the unit price per carat. That's why a 2 carat diamond is more than double the price of a 1 carat diamond.

Example:
Diamond "A" = 0.25 carats and costs $1,000 per carat.$1,000 x 0.25ct = $250/stone.
Diamond "B" = 0.50 carats and costs $1,250 per carat.$1,250 x 0.50ct = $625/stone.

It is important to understand that when you compare two diamonds of the same shape, the one having a larger carat weight does not always translate to the larger looking stone. Dimensions play an important role in the diamond's appearance.


Clarity

Clarity is a measure of internal defects of a diamond called inclusions. Inclusions may be crystals of a foreign material or another diamond crystal, or structural imperfections such as tiny cracks that can appear whitish or cloudy. The number, size, color, relative location, orientation, and visibility of inclusions can all affect the relative clarity of a diamond. The Gemological Institute of America (GIA) and other organizations have developed systems to grade clarity, which are based on those inclusions which are visible to a trained professional when a diamond is viewed under 10x magnification. Diamonds become increasingly rare when considering higher clarity grading. Only about 20% of all diamonds mined have a clarity rating high enough for the diamond to be considered appropriate for use as a gemstone; the other 80% are relegated to industrial use. Of that top 20%, a significant portion contains one or more visible inclusions. Those that do not have a visible inclusion are known as "eye-clean" and are preferred by most buyers.

The following is the GIA Diamond clarity-scale:

FL-Flawless

These stones have no imperfections inside or on the outside of the stone under the magnification of a loupe of 10 power.

IF-Internally Flawless

These stones have no inclusions under a loupe with a 10 power magnification.

VVS1,VVS2-Very Very Slightly Imperfect

These stones have very small inclusions which are very  difficult to see under a loupe with a 10 power magnification.

VS1,VS2-Very Slightly Imperfect

These stones have small inclusions which are slightly difficult to difficult to see under a loupe with a 10 power magnification.

SI1,SI2-Slightly Imperfect

These stones have inclusions which are fairly easy to see under a loupe with a 10 power magnification, or visible to the naked eye.

I1,I2,I3-Imperfect

These stones have inclusions which range from eye visible to very easily seen to the naked eye.

Here is a table summarizing clarity grades:

Clarity FL IF VVS1 VVS2 VS1 VS2 SI1 SI2 I1 I2 I3
Scale Flawless-
Internally Flawless
Very Very Slightly Imperfect Very Slightly Imperfect Slightly Imperfect Imperfect



Color

The most fine quality as per color grading is totally colorless which is Graded as "D" color diamond across the globe which means it is absolutely free from any color. The next is very slight traces of color which can be observed by any expert. However when studded in the jewelry these very light colored diamonds do not show any color or it is not possible to make out color shades. These are graded as E color or F color Diamonds. Diamonds which show very little traces of color are graded as G or H color diamonds. Slightly colored diamonds are graded as I or J or K color. A diamond can be found in any other color also other than colorless. The scale begins with the letter D, representing colorless, and continues, with increasing presence of color, to the letter Z. Diamonds are color-graded by comparing them to stones of known color under controlled lighting and precise viewing conditions. Many of these color distinctions are so subtle that they are invisible to the untrained eye. But these slight color differences make a very big difference in diamond quality and price.




Cut

Diamond cutting is the art and science of creating a gem-quality diamond out of mined rough. The cut of a diamond describes the manner in which a diamond has been shaped and polished from its beginning form as a rough stone to its final gem proportions. The cut of a diamond describes the quality of workmanship and the angles to which a diamond is cut. Often diamond cut is confused with "shape". There are mathematical guidelines for the angles and length ratios at which the diamond is supposed to be cut in order to reflect the maximum amount of light.

The most popular standard diamond cuts are: