The Four Cs
Fine diamonds are among the most coveted of all gems. Their value however, differs widely from one diamond to another. Experts evaluate every diamond for rarity and beauty, using four primary guidelines. These are called The Four Cs – Cut, Color, Clarity, and Carat Weight.
When you think of the cut, you probably think of the shape of the diamond. You are partially correct. While cut does refer to shape, it also refers to the proportions of how the diamond is actually cut.
The most popular shapes include Round, Oval, Square, Princess, Emerald, Baguette and Marquise cuts.
With the exception of fancy colored diamonds, the most valuable diamonds are those with the least color. The color scale for transparent diamonds goes from D-F (colorless), G-J (near colorless), K-M (faint yellow), to Z (light yellow). Completely colorless diamonds are rare.
A diamond’s clarity is measured by the existence, or absence, of visible flaws. Tiny surface blemishes or internal inclusions – even those seen only under magnification with a 10x jeweler’s loupe – can alter the brilliance of the diamond and thus, affect its value. Clarity levels begin with Flawless followed by Very Very Slight, Very Slight, Slightly Included, and Included.
The size of a diamond is measured, not by its dimensions, but by weight. One carat, the traditional unit of measurement for diamonds, is equal to approximately 0.2 grams. You may also hear the weight of a diamond referred to in points. A point is equal to 1/100 of a carat; therefore, a 75-point diamond equals 0.75 carat. Diamonds of equal weight may appear slightly different in size, depending on their depth and proportions. Because they are quite rare, larger diamonds of gem quality are much more valuable.