CARAT
One carat corresponds to a weight of 0.2 grams in jewelry, providing a universal unit of measurement for all diamonds.
The term “carat” originates from the carob seed, which has a remarkably consistent weight and was historically used as a standard in trade.
For diamonds weighing less than one carat, each carat is divided into 100 points, similar to cents in a euro. For example, 0.75 ct equals 75 points, 0.5 ct equals 50 points, and so forth.
It’s important to note that the diamond price scale is not linear—1-carat diamonds are significantly rarer than 0.5-carat stones, so their price per carat is proportionally higher.
COLOR
The color scale for white diamonds ranges from D (colorless) to Z (light yellow or brown).
Truly colorless diamonds, containing no nitrogen traces in their chemical composition, are extremely rare. Most diamonds used in jewelry are nearly colorless, with very slight yellow undertones. Color grading is done by comparing each diamond to a set of reference stones and assigning a letter that corresponds to its hue.
Diamonds also come in a wide spectrum of colors and shades, known as fancy colors.
Fluorescence
Invisible in daylight, some diamonds can emit a visible glow when exposed to ultraviolet light. While fluorescence does not affect a diamond’s color grade, it can be noted as an additional identifying feature on laboratory certificates.
CLARITY
The diamond clarity scale comprises eleven grades, ranging from flawless (FL) to I3 (heavily included).
Since diamonds form under extreme heat and pressure, it is extremely rare to find one completely free of internal or external characteristics.
These natural features, resulting from the diamond’s formation, help gemologists distinguish genuine diamonds from imitations and make each stone uniquely identifiable. Inclusions are rarely visible to the naked eye and typically require expert examination with a 10x magnifying loupe.
Every laboratory-issued certificate includes a detailed map or description of the inclusions present in the diamond, aiding in its authentication.
CUT
The GIA laboratory’s cut quality scale includes five grades, ranging from Excellent to Poor.
The beauty of a cut and polished diamond lies in its intricate relationship with light. This exceptional appearance results from three key characteristics:
Brilliance: the combined reflection of white light from the diamond’s surface and interior; Fire: the colorful flashes emitted when light disperses within the stone; and Scintillation: the contrast between light and dark areas that creates sparkle.
A diamond’s proportions are crucial, as they determine how it interacts with light, directly influencing its beauty and overall appeal. Diamonds with excellent proportions, symmetry, and polish maximize light performance, resulting in enhanced brilliance, fire, and scintillation.