Introduction to Diamonds

Are diamonds really a girl's best friend? You betcha! Sparkly and spectacular, they represent love and romance, and mark the most special of milestones. Like women themselves, they come in all sizes and shapes – and truly flawless ones are extremely rare (and the ones that cost the most, natch).

Believe it or not, bigger isn't always better when it comes to diamonds (just don't tell the Kardashians). The 4 C's, as they're known—cut, clarity, carat and color -- will tell you all you need to know about purchasing the right diamond for you.

Here are some of the most popular shapes of cut diamonds:

While there are other shapes, these are the most sought after. Round brilliant diamonds are by far the favorites, accounting for four of every five diamonds purchased.

Cut: The Source of The Sparkle

Of the 4C's of diamond ratings, cut is considered the most critical. Really, the sparkle and brilliance of a diamond is all in how its cut—which is an art as much as a science, and is not just about the shape.

Two things you need to know about the quality of the cut: Reflective Powers and Proportion.

• The best-cut diamonds reflect the most light, making them the most bright and brilliant stones. The lower quality gems are cut in a way that makes it difficult for light to enter and reflect, making them appear less sparkly.
• And the better the proportion of the diamond, the better the light reflection. The most spectacular, and costly, diamonds are the ones that are more perfectly proportioned. A shallow cut diamond, for example, where the bottom half lacks a certain depth, will not reflect light in the most optimal way.

Color: Why a "D" (or E or F) Grade is Great

Light makes right, when it comes to diamond color ratings. The purest of diamonds are actually the most colorless of them all. The presence of colors, like reds, blues or violets, clash with the gem's sparkle capabilities. The exception to this rule is rare fancy colored diamonds, called "Fancies" (love that name), that are sought after for their deep hues -- and fetch a "fancy" price.

Some things you need to know about color rating:

1. Gems are rated on a color scale of D through Z. It's probably the one time in your life that you actually want a "D," or an "F" grade since D, E and F's are considered the highest quality diamonds.
2. To the untrained eye it's almost impossible to distinguish the shade variations of diamonds. G-J diamonds are more common and being near colorless can offer the customer better value.

Clarity: One of a Kind

Like all of us have flaws, so do most diamonds. The clarity rating refers to the size, number and placement of these flaws, or blemishes, usually referred to as "inclusions". These inclusions are what make each diamond utterly unique. Not surprisingly, the least flawed diamonds are the most valuable and the completely flawless ones are really rare, and really costly.

Carats: Weight for Me

Carat, probably the C that people are most familiar with, refers to the weight of the diamond and not the size, although the weight is generally indicative of the size of the gem. However, two diamonds of equal weight can appear very different depending on the cut and clarity.

Some things to keep in mind:

• Larger diamonds, always rarer than smaller ones, are not simply priced proportionately more. Because of its rarity, a two-carat diamond, for example, will cost way more than two one-carat stones of equal quality.
• Diamonds come in different increments. And for rings, or other pieces of jewelry, that have more than one diamond, the total weight of the gems is often given as Total Carat Weight (TCW).