4Cs

Diamond Color, Clarity, Cut and Carat Weight are collectively termed the 4Cs – the factors that, when combined, define a diamond’s quality and ultimately determine its value. GIA created the 4Cs of Diamond Quality, which has become the universal method for assessing the quality of any diamond, anywhere in the world. The creation of the 4Cs means that diamond quality can be communicated in a universal language so diamond purchasers know exactly what they are buying.

Color

GIA’s diamond color grading system measures the absence of color, starting with D as colorless and continuing to Z representing light yellow or brown. The distinctions between color grades are so subtle that they are often invisible to the untrained eye but can make a big difference in diamond quality and price.

Cut

A diamond’s cut determines its sparkle. To fashion a stone with proportions, symmetry and polish worthy of an excellent cut grade requires artistry and workmanship. The finer the cut quality, the more sparkle the diamond has.

Clarity

Natural diamonds form from carbon exposed to tremendous heat and pressure deep in the earth. Diamonds often contain clarity characteristics, called inclusions or blemishes. Inclusions are enclosed within the gem and blemishes are on the surface of the diamond. If all else is equal, the closer a diamond is to flawless, with no inclusions or blemishes, the higher its value.

Carat Weight

Diamond weight is measured in carats. One carat is equal to 0.2 gram, about as heavy as a paperclip. Since larger diamonds are more rare, they will cost more than a smaller gem with the same color, clarity and cut grades.

GIA Grading Report

The GIA Diamond Grading Report includes an assessment of a diamond’s 4Cs – Color, Clarity, Cut and Carat Weight – along with a plotted diagram of its clarity characteristics and a graphic representation of the diamond’s proportions. The GIA Diamond Dossier® includes these without the graphical representation of the clarity characteristics. The GIA laboratory issues diamond grading reports for loose, natural diamonds in the D-to-Z color range that weigh 0.15 carats or more.

Diamond Fluorescence

Fluorescence is the visible light some diamonds emit when they are exposed to invisible ultraviolet (UV) rays. On a GIA diamond grading report, fluorescence refers to the strength, or intensity, of the diamond’s reaction to longwave UV, which is an essential component of daylight. The light emitted lasts as long as the diamond is exposed to the ultraviolet source.

Laboratory-grown diamonds

A lab-grown diamond (sometimes called man-made or synthetic diamond) is the result of a technological process, as opposed to the geological process that creates natural diamonds. Lab-grown diamonds have essentially the same chemical composition, crystal structure, optical and physical properties of diamonds found in nature. Most lab-grown diamonds are categorized as either high-pressure, high-temperature (HPHT) or chemical vapor deposition (CVD) diamonds, depending on the method of their production. Since HPHT and CVD diamonds grown in a laboratory are virtually identical to natural diamonds, differences only become clear when they are analyzed in a gem laboratory.