As with any precious stone, when grading diamonds the “4 C´s” – Color, cut, carat, clarity – are taken into account in order to determine value. However, of these four characteristics, it is generally accepted that cut has the greatest impact on a diamond’s overall appearance.
When it comes to color, diamonds are graded on a scale from D (no hue) to Z (a yellowish hued stone). The less color a diamond has, the more valuable it is considered to be. However, it should be noted that some diamonds with a yellow or brown tinge can actually be quite beautiful, and thus may be valued highly despite being lower on the color scale.
Cut is arguably the most important factor in determining a diamond’s beauty. A well-cut diamond will exhibit brilliance (the amount of white light reflected back to the viewer), fire (the dispersion of light into the colors of the rainbow), and scintillation (the “sparkle” of the diamond as it is moved). A poorly cut diamond, on the other hand, will appear dull and lifeless.
The weight of a diamond is measured in carats. One carat is equal to 200 milligrams. The more carats a diamond weighs, the more valuable it will be. However, two diamonds of equal carat weight can have very different values depending on the other “C´s.” For example, a one carat diamond with poor clarity and color will be worth far less than a one carat diamond with excellent clarity and color.
Finally, diamonds are graded for clarity on a 6 point scale, from flawless (no inclusions or blemishes visible to the naked eye) to included (visible inclusions or blemishes). Again, the more flawless a diamond is, the more valuable it will be.
Keep in mind that these are only general guidelines. When determining the value of a diamond, a trained professional will take all of the above factors into account, as well as any unique characteristics that might impact the stone’s desirability.