The complete guide to diamond grading
Every diamond is unique, like a snowflake. Until the mid-20th century, there was no standard for evaluating diamonds. Today, the 4Cs represent the universal method for classifying the quality of any diamond, anywhere in the world.
Carat · Color · Clarity · Cut
Diamond weight is measured in carats (ct). One carat equals 0.20 grams and is divided into 100 points.
Color evaluation is based on the absence of color. A perfect diamond is colorless like a drop of pure water.
Clarity indicates the absence of internal inclusions and external imperfections, evaluated with 10x magnification.
The cut determines how the diamond reflects light. A perfect cut maximizes the brilliance of the stone.
The carat is the unit of measurement for diamond weight. One carat equals 0.2 grams or 200 milligrams. The term derives from carob seeds, used in ancient times as a unit of weight due to their surprising uniformity.
Weight significantly influences the value of a diamond, but it is not the only determining factor. Two diamonds of the same weight can have very different values based on cut, color, and clarity.
Color in diamonds refers to the absence of color. A chemically pure and structurally perfect diamond is completely transparent, without any hue. The GIA grading system uses a scale from letter D (colorless) to Z (colored).
The evaluation is done by comparing the diamond with certified reference stones, called "Master Stones". Color differences are often so subtle that they are invisible to the naked eye.
| Colorless | D | E | F | |
| Near colorless | G | H | I | J |
| Faint color | K | L | M | |
| Light color | N-R | S-Z |
Clarity indicates the absence of inclusions (internal characteristics) and blemishes (external characteristics). A diamond is considered "flawless" when at 10x magnification it shows no visible defects.
Natural diamonds form deep within the Earth, exposed to extreme heat and pressure. This process can create a variety of internal characteristics called "inclusions" and external characteristics called "blemishes".
Internally Flawless - No inclusions visible at 10x magnification
Very Very Slightly Included - Inclusions so small that they are difficult to detect even for an expert
Very Slightly Included - Inclusions difficult to observe at 10x magnification
Slightly Included - Inclusions evident at 10x magnification but not visible to the naked eye
Included - Obvious inclusions that can affect transparency and brilliance
Cut is often considered the most important of the 4Cs because it has the greatest impact on a diamond's beauty. The quality of the cut determines how well the diamond captures and reflects light.
A well-cut diamond displays three optical attributes: brilliance (white light reflected), fire (dispersion of light into rainbow colors) and scintillation (light play when the diamond moves).
Our expert gemologists are at your disposal to help you choose the perfect diamond.