Buying a diamond (or any precious gem) doesn't have to be an overwhelming experience. Probably the most basic thing to know is what is known as "the 4 C's" - cut, color, clarity and carat.

Cut

The brilliance of a diamond depends heavily on the cut. The cut refers to the diamonds refractory qualities (or what makes a diamond sparkle), not the shape of the diamond (round, emerald, princess, etc.) The quality of the cut makes a big difference in how a diamond looks. A good cut gives the diamond its brilliance, the "flash and fire" that we want to see from the magnificent stones.

The above diagram shows the anatomy of a cut. Light enters the table and travels through the pavilion, where it is reflected from one side to the other before reflecting back out of the diamond through the table and to the observer's eye, producing the flashy, fiery effect that makes a diamond so alluring.

If the pavilion is too shallow or too deep, the light does not refract properly. It will reflect out the sides or the bottom instead and loses the flash and fire characteristics that are such an essential part of the diamond experience.

Variance in proportions can be difficult for an amateur to ascertain, even if you are well read on the subject. Buying a diamond that has been GIA certified takes a lot of the guesswork out of buying diamonds, but very few diamonds are certified by GIA or any other certifying agency.

The GIA has detailed information on diamond anatomy.

Color

Color refers to the presence or absence of color in white diamonds. There are colored diamonds but the grading scale refers to white diamonds. A colorless diamond, because it allows more light to pass through than a colored diamond, emits more sparkle and fire. The whiter a diamond's color, the greater its value.

Most diamonds found in jewelry stores run from colorless to near-colorless with slight hints of yellow or brown. Fancy color diamonds are the exception and run outside this range. This article is about white diamonds (fancy color diamonds and other colored stones will be covered in other articles).

The color grading scale beings with D, which represents a colorless white diamond, and travels down the alphabet to Z. Diamonds rated D through F are the most valuable and desirable because of their rarity. Diamonds rated G through I show virtually no color that is visible to the untrained eye and would be a perfectly acceptable choice.

Clarity

Clarity refers to the presence or absence of inclusions within or blemishes on a gemstone. For the purposes of grading, all flaws are called inclusions.

Inclusions include flaws such as air bubbles, cracks, and non-diamond minerals found in the diamond. Blemishes include scratches, pits, and chips. Diamonds with no or few inclusions and blemishes are more highly valued than those with less clarity because they are more rare. The clarity rating scale is as follows:

• F
  Flawless: No internal or external flaws. Extremely rare.
• IF
  Internally Flawless: no internal flaws, but some surface flaws. Very rare.
• VVS1-VVS2
  Very Very Slightly Included (two grades). Minute inclusions very difficult to detect under 10x magnification by a trained gemologist.
• VS1-VS2
  Very Slightly Included (two grades). Minute inclusions seen only with difficulty under 10x magnification.
• SI1-SI2
  Slightly Included (two grades). Minute inclusions more easily detected under 10x magnification.
• I1-I2-I3
  Included (three grades). Inclusions visible under 10x magnification AS WELL AS to the human eye. Buying a diamond with this grade of clarity isn't recommended.
  

For grades F through SI, the clarity grade affects a diamond's value, not the diamond's unmagnified appearance.

Diamonds in the VVS and VS range are excellent choices if you have the money to spend on the higher grade. However, on a budget, the SI grade is very acceptable, as the inclusions are not visible to the naked eye.

Carat Weight

A carat is a unit of measurement, it's the unit used to weigh a diamond. One carat is equal to 200 milligrams, or 0.2 grams. We all know that the larger the diamond, the higher the price.

Up to 1 carat weight, you will find diamonds reasonably affordable in all cuts, clarity and color ranges. The price rises dramatically at the 1-carat mark. If you are on a budget but really want a flashy, you may want to consider looking for a diamond that is just under (but close to) 1 carat in weight or go with less carat weight but a better grade of cut, clarity and color to ensure the flash and fire that make diamonds of any size a pleasure to look at.

This is just the short lesson on the 4 C's. We'll be going into more detail in additional articles, but this is enough to get you started on your journey!