4 C's of Diamonds
Carat WeightCarat is the easiest category on this list to describe: Carat is the measurement of weight for diamonds, with one carat weighing 0.2 grams. A carat is divided into 100 points. So, for example, a 250-point diamond would be 2.5 carats.
Remember that while a carat is the same weight no matter the shape of the stone, a diamond can appear larger or smaller depending on the dimensions of the stone. For example, a one-carat emerald-cut diamond will look far larger than a one-carat round-cut diamond because the same amount of diamond is elongated and faceted in a way that creates a long, flat table.
ColorDiamonds are most beloved when they’re pure and water-clear. But in nature, there are very few diamonds that come out of the Earth completely clear. Because diamonds are, fundamentally, stones, they’re formed by random physical processes and have other elements trapped in them during their creation. The most common addition is the gas nitrogen, which causes shades of yellow or brown. And because nitrogen is such a common part of Earth-grown diamond, it’s rarer to find colorless stones and the price of them reflects that.
GIA offers a color scale for measuring diamonds ranging from utterly colorless D to a very yellow Z. Do keep in mind, though, that when the saturation of yellow passes Z or the diamond is another color like green or purple, GIA labels these stones as “fancy” and offers another rating scale for them.
CutCut doesn’t refer to the shape of a diamond, but the two things are related. When a diamond is faceted to design a shape, there are mathematical standards for that particular shape that demand a predetermined ratio of crown, girdle, and pavilion to maximize the internal reflectivity and minimize the light loss of a jewel-quality diamond.
When it comes to choosing a diamond, the GIA has collected ideal proportions and allowable variance that moves a given jewel from “excellent” to “poor” using a seven-point measuring scale: brightness, fire (rainbow sparkle), scintillation (white sparkle), weight ratio, durability, polish, and symmetry.
Clarity“Clarity” is the term used to describe how many inclusions (or how few) there are in a diamond. As with color, the clarity of diamonds is wildly divergent due to being grown in nature. From industrial-quality stones to flawless diamonds, clarity is rated on a sliding scale. Inclusions that can be found in diamonds include cracks, voids, dents, or solids trapped in the stone during its formation. Materials like black carbon, olivine, garnet crystals, silica, iron, and gypsum can grow inside a diamond. These inclusions, including their density, placement, and visibility, change a diamond's clarity grade and the cost accordingly.
The clarity scale by GIA features 11 detailed categories, ranging from ranging from F (flawless), which means that a certified grader can’t see inclusions using 10x magnification; to I3 (included-3), which means that a grader can see numerous, easily visible inclusions.