Buying diamond jewelry is confusing. It isn't easy to tell good stones from bad - that is, without special training and a jewelers' loupe. Gemologists use a diamond ranking system. By understanding this system, and what the letters mean, you can choose the perfect diamond. Read on to learn about the "4 Cs" -- color, cut, clarity, and carat weight.

Completely colorless diamonds are the most valuable, and the rarest. Most "clear" stones contain small amounts of color. A one-letter designation classifies diamonds according to the amount of color, if any, they contain. The highest rating for colorlessness is D, with E and F close behind. These colorless stones are very rare. The scale continues past near-colorless (G-J), faint yellow (K-M), very light yellow (N-R), and to light yellow (V-X). Diamonds graded from G to I have virtually no color visible to the untrained eye. Color choice may be more important when placing the stone in a sterling silver, white gold, or platinum setting, where a diamond's yellow tint would be more noticeable.

Cut does not refer to the overall shape of the stone (as seen in round or pear-shaped gems). Rather, cut refers to the reflective quality of the diamond. A well cut diamond catches and reflects the light, with a brilliant sparkle. Poorly cut diamonds have less sparkle. The cut of a diamond is rated to help consumers choose a stone. These grades are:

- Ideal

- Premium

- Very Good

- Good

- Fair and Poor

Your choice is determined by your budget and preferences.

Clarity

Diamonds are natural materials, and it is common for them to contain small imperfections. Inclusions are imperfections inside the gemstone, while blemishes affect the outside. Jewelers use a 10x loupe (a magnifying device) to inspect and grade stones. The grading is as follows:

- F: Flawless. Almost unimaginably rare.

- IF: Internally Flawless. There may be some surface flaws, but the diamond is perfect inside. This is very rare.

- VVS1 - VVS2: This is actually two grades of Very Very Slightly Included. These stones have tiny inclusions not easily detected by trained professionals.

- VS1 - VS2: Two more grades, Very Slightly Included. Small imperfections are hard to spot.

- SI1 - SI2: Two grades of Slightly Included, with small imperfections a little easier to see with magnification.

While the value of a diamond increases with its clarity, it's important to know that the imperfections contained in grades F through SI are not visible to the naked eye. There are also three grades of Included (I1 - I3), which contain imperfections that can be visible.

Carat Weight

Diamonds are measured in carats, with one carat equal to 0.2 grams. The largest cut diamond in history is Cullinan1, Star of Africa, weighing in at a whopping 520 carats. Currently, it is set in the scepter of King Edward VII - worthy of royalty indeed! Your budget (or scepter) may be smaller, so don't let size be the only factor you consider. The setting you choose has to comfortably fit the stone, neither too small nor too large. Also, precious stones look larger when worn by someone with small, slender fingers.

The four Cs - color, cut, clarity, and carat weight - are important considerations when buying diamond jewelry. With this information, you can begin to make sense of confusing letter grades. Need more help? Please feel free to contact me.