Cut

A diamond’s ability to sparkle is strictly reliant upon its cut. Cut does not reference the shape of the diamond. Instead, cut refers to the way the diamond is cut: how many facets are used to maximize the diamond’s brilliance and the proportion of the diamond, among other details.

Three factors that determine a diamond’s cut grade are solely appearance-based aspects. The first, brightness, is defined as the total light that is reflected from the diamond or the white light reflections that a diamond emits. A very bright diamond returns lots of light from a “face up” position. A diamond with the best brilliance returns the greatest amount of light from the bottom of the diamond, called the crown, to the face up position, which is the top of the diamond. The second determining factor, fire, is the amount of dispersion of light into the colors of the spectrum that radiate from the diamond. Interestingly, the amount and quality of fire emitted from a white diamond is a direct result of its symmetry and proportion. Finally, scintillation is the pattern of light and dark areas and the flashes of light or sparkle when a diamond is moved.

Other determining factors deal with the diamond’s actual design and craftsmanship: weight ratio, durability, polish, and symmetry.

The official GIA Cut Scale for round brilliant cut diamonds. Illustration: GIA.edu

Color

White diamonds actually exist in a color range of their own, from technically void of any color to those with smaller amounts of the trace element nitrogen that give the stone a slight yellowish, brown tint. Color is potentially one of the most important Cs when determining the value and rarity of a white diamond. The subtlest differences in color can affect a diamond’s value.

While diamonds will often be verbally referred to as the letter grade by which they were assigned to during diamond certification, the D to Z color grading scale, they might also be described with the degree of how colorless the stone is. These descriptions directly correlate to the color grade that the stone may have:

The official white diamond grading scale, D-Z. Illustration: GIA.edu

Carat

One carat is equal to 100 points, and each point is two milligrams, or 0.2 grams. Surprisingly, one carat is about the same weight as a paperclip. In other words, if you are holding a 1.50-carat gemstone, then the gemstone weighs 150 points, 0.3 grams or 300 milligrams. In the jewelry market, diamonds with a carat weight greater than one are expressed in decimals. Because even a fraction of a carat can make a big difference in price, carat weight is measured to the thousandth place and then rounded to the hundredth place.

Clarity

Extremely important in the grading and determination of the value and rarity of a diamond, clarity also helps establish the diamond’s unique identity. The technical definition of clarity is simple: a gemstone’s relative freedom from inclusions and blemishes. Inclusions are the clarity characteristics within the diamond, which can occur at any stage during a white diamond’s development and may potentially extend to the diamond’s surface. Blemishes, or external clarity characteristics, can occur at any stage after the diamond’s formation. The number, position, nature and size of clarity characteristics directly correlates to the diamond’s value. The GIA clarity scale includes 11 grades ranging from flawless to Included or I3.

 

Illustration: GIA.edu

To learn more about the Four Cs, read our guide, The Four Cs: What to Consider Before Purchasing a White Diamond.