The 4C's and beyond
This is probably most important when it comes to determining a diamond’s value and beauty. It shows the skill of the cutter who fashioned the diamond to bring out the brilliance and fire of the diamond that makes it sparkle from across the room. Technology can be used to assess the diamond’s light performance and hence the quality of its cut. A diamond’s light performance depends on the cutter’s decision of angles and placement of the facets, as well as the skill to place those facets precisely. Achieving a diamonds full luster takes time and careful polishing. Like minute scratches that dull a glass surface, a poor polish can reduce the brightness and sparkle of a diamond. The quality of the cut also affects a diamond’s value, and can significantly increase or decrease the stones market price. A well cut diamond will have more scintillation (Sparkle) and/or fire (prismatic light splitting effect), making it more captivating to the eye.
Most diamonds possess varying degrees of coloration - truly colorless diamonds are more rare and valuable. Subtle differences in color can make a substantial difference in value. A well-cut diamond can refract and disperse light enough to disguise certain degrees of coloration. For this reason, diamond color is typically graded by viewing the stone from the back instead of from the top down.
There are also fancy colored diamonds that are prized because of their unusual color. Diamonds can be enhanced by man to achieve a desired color if conditions are correct, but naturally fancy colored diamonds are rare and can be more valuable than their colorless and near colorless counterparts. Diamonds can come in almost every color imaginable – from the faintest shade of pastel pink, blue, or yellow to the most vivid shade of brown, green, or orange. As color intensity increases, the diamond becomes more rare and valuable.
Clarity is based on the number of inclusions and blemishes inside and on the surface of the diamond. Most inclusions are crystals (tiny materials in the diamond) and feathers (visible inconsistencies in the crystal structure).When grading for clarity, the grader uses 10x magnification to evaluate the size, location, number, and color of all inclusions and blemishes. Though inclusions and blemishes don't always affect a stone’s beauty, they do affect its price. No two diamonds will have the same inclusions so a stone plot can be done to document the diamonds “fingerprint” for future identification.
Carat refers to the weight of a diamond – one carat equals 100 points. The larger the stone, the more rare it is and the greater its value. If a diamond is improperly cut, added carat weight may reduce its brilliance. In other words, a diamond with less carat weight may be worth more if it is cut better, thus having more sparkle.