Understanding the Four Cs
Cut Cut, quite simply, refers to the shape of the diamond. Diamonds can theoretically be cut into any possible shape, but there are a few styles that have become popular over the years, due to how they reflect and refract light within the stone. Round cuts are the most popular, with princess cuts (or square cuts) and cushion cuts (rectangular with rounded corners) not far behind. These cuts provide a huge amount of sparkle and flash within the stone. Step cuts, on the other hand, such as emerald cuts and baguette cuts, show more straight lines inside the stone, and provide a more "geometric" appearance.
Clarity Every diamond contains tiny flaws within its crystal structure, and the clarity grading tells a buyer how visible these flaws are. The ratings begin with "F" and "IF" (flawless and internally flawless), where there are no blemishes or inclusions visible under 10x magnification. On the other end of the scale is three levels of "I" (included), where the inclusions are actually visible with the naked eye. Bear in mind, however, that even diamonds with a "lower" clarity grade may not contain flaws you can see without the aid of a microscope or a jeweler's loupe.
Color This letter grading (D through Z) generally only refers to how "white" or "colorless" a diamond is, and not to whether it's blue or pink or green. A rating of D means that there is no detectable traces of color within the stone. The further down the alphabet you go, the more "yellow" the color can appear. This is not always a case of "whiter is better," though, as many people prefer the warmth and softness of a less "colorless" diamond to the cold and harsh brilliance of a purely "white" stone.
Carat Many people equate carat with the apparent size of the diamond, but technically, carat means weight. One carat equals 200 milligrams. Naturally, a heavier diamond will likely be larger, but other factors can affect apparent size, such as shape, depth of cut, and a halo setting of smaller stones (which can make the main stone of some diamond engagement rings look larger). For smaller stones, many jewelers employ a point system to describe carat weight, where 100 points make up a carat. So a 10-point stone would weigh one-tenth of a carat.
Wading through cases and cases of diamond engagement rings can be a daunting task. Every bit of information helps, and hopefully you feel a little better armed in your search. Happy hunting!