The 4 C's of Diamonds
A diamond's value is based on four main characteristics known as the "4 C's". Clarity, color and cut (proportion) together with the carat weight determine the value of a stone. While clarity is frequently assumed to be the most important factor of the 4 C’s, in actuality, color and cut (particularly cut) have a more profound effect on the visual appearance of a diamond.
A diamond’s size is indicated by its weight, and the weight is indicated in carats: one carat equals 1/5 of a gram. The word carat is often abbreviated as ct. If a diamond weighs less than one carat, its weight is indicated in points (1/100 of a carat). Therefore, a half-carat stone weighs 50 points, while a 75 point diamond is 3/4 of a carat. If a diamond weighs more than one carat, its weight is expressed in carats and decimals. Therefore, a 1.07 ct. stone weighs one carat and 7 points. The price of a diamond tends to jump when its carat weight crosses 50 points, 75 points or 1 carat. The price difference between a diamond that weighs 49 points and one that weighs 50 points is often greater than the price difference between one weighing 48 and 49 points. The larger a diamond, the more rare it is. Therefore, as carat weight increases, so does the price per carat. A 2-ct. stone, for example, will be more than twice that of a 1-ct. stone, assuming they are similar in cut, clarity and color.
Diamond color is all about what you can’t see. Diamonds are valued by how closely they approach colorlessness – the less color, the higher their value. The exception to this is fancy-color diamonds, such as pinks and blues, which lie outside this color range. It may appear that your diamond is colorless, but in fact, it probably has tinges of yellow or brown. A diamonds color refers to how noticeable its tints are. The more noticeable the color, the lower its value the less noticeable the color, the more rare it is and the higher its value. There is an exception to this rule: If your diamond has tints of a color other than yellow or brown - for example, if it is blue, purple or red - it is considered to be fancy-colored, and is graded differently