MASSIMO CAVALLI 1883

DIAMOND GUIDE

A simple and complete guide to understanding diamonds : from the 4Cs (cut, color, clarity and carat) to certifications , right down to the details that make the difference in choosing the perfect stone .

THE 4C'S OF DIAMOND

A diamond is a crystalline form of carbon. What sets it apart from other carbon structures is the specific arrangement of its atoms. Natural diamonds are formed deep within the Earth’s mantle—between 85 and 115 miles (approximately 136 to 184 kilometers) below the surface - under extreme pressure and temperature, and in the absence of oxygen. Their journey to the Earth’s surface takes millions of years. It’s also worth noting that diamond is the hardest naturally occurring material on Earth.

Rough diamonds are mainly sourced from Southern Africa, Australia, Siberia, Canada, and Brazil. Their natural color ranges from yellow, gray, or brown to completely colorless. On rare occasions, diamonds can be found in shades of blue, green, black, pink, violet, and orange. The rarest diamonds are red.

Understanding diamonds starts with the four fundamental characteristics known as the 4C’s: Carat (weight), Color, Clarity, and Cut. These features are essential tools for grading, comparing, and ultimately pricing diamonds—from rough stone to retail purchase. Choosing the right diamond is often a balance between these elements and the budget available.

In short, a diamond’s price is based on its rarity, and the 4C’s define how rare and unique each stone is. Diamonds are highly valuable precisely because they are rare.

“No two diamonds are alike.”

Carat refers to the weight of a diamond. One carat is equal to 0.2 grams, meaning a five-carat diamond weighs one gram. A carat is subdivided into 100 points, so a diamond weighing half a carat is often described as a 50-point diamond.

As previously mentioned, a diamond’s rarity plays a central role in determining its value. In general, as carat weight increases, so does rarity—and therefore price. Larger diamonds are significantly rarer (assuming all other quality factors remain equal), which is why price tends to rise exponentially with weight.

It’s also important to note that carat weight does not always equal visual size. The cut of a diamond greatly affects how large it appears. Two diamonds with the same weight may look quite different depending on how they’re cut.
Depending on their unique chemical composition, diamonds can display subtle variations in hue. The most common shades—yellow and brown—are caused by the presence of nitrogen atoms within the crystal structure. Distinguishing between two color grades can be challenging, especially for the untrained eye, as the differences are often very subtle.
La purezza di un diamante indica il grado di impurità interne (inclusioni). Le inclusioni si formano naturalmente durante la crescita del cristallo, mentre i difetti superficiali possono derivare sia da processi naturali che dall’intervento umano, ad esempio durante la fase di taglio, o per via di colpi subiti.

Quasi tutti i diamanti presentano almeno qualche imperfezione. La valutazione della purezza avviene con una lente d’ingrandimento a 10x, standard nel settore. Più elevata è la purezza, maggiore sarà la rarità e il valore della pietra.
The cut of a diamond refers to how it has been shaped and polished from the rough stone. It includes both the style or shape—such as round brilliant, emerald, Asscher, pear, or oval—and the precision of the cut: proportions, symmetry, angles, and overall finish. These factors directly influence how well the diamond reflects light, contributing to its brilliance, fire, and overall beauty.

When proportions or symmetry are off—such as a pavilion that is too shallow or too deep—light escapes instead of being reflected back to the viewer. As a result, the diamond loses brilliance and sparkle.
The quality of a cut is entirely dependent on the skill of the diamond cutter. A well-executed cut doesn’t simply depend on the number of facets, but on how expertly they are arranged to maximize the diamond’s brightness, scintillation, and visual appeal. The expert’s main objectives are to deliver optimal brilliance and to maximize the perceived size of the stone.

There are three primary cut styles:

Brilliant cut – The most popular cut, designed to enhance maximum brilliance through a complex facet arrangement (e.g., round brilliant).

Step cut – Recognizable by rectangular or square outlines and parallel, straight facets (e.g., emerald cut, Asscher cut).

Mixed cut – A combination of brilliant and step cut styles, designed to balance brilliance and size. The radiant cut is a typical example.

Brillance

According to research by the GIA (Gemological Institute of America), a diamond’s brilliance—the quality that gives it that eye-catching sparkle—is the result of a combination of three main visual components: brightness, fire, and pattern.

These aspects are evaluated by experts without the use of magnification.

Brightness refers to the return of white light to the viewer’s eye.
Fire describes the flashes of rainbow colors created by the dispersion of white light.
Pattern is the arrangement and contrast of light and dark areas caused by reflections from the diamond’s crown facets.

These elements work together in a well-cut diamond to enhance its visual performance and make sure that the proportions maximize the stone’s size and sparkle. Because brilliance is what people most immediately notice when they look at a diamond, it is considered the top priority in cutting.

Diamond Grading & Certification Laboratories

Grading certificates provided by independent gemological laboratories act as a diamond’s “passport”—a detailed record of its quality characteristics.

Among the most respected labs in the industry are GIA (Gemological Institute of America), HRD, and IGI. These institutions follow strict and consistent grading standards, making them the most trusted sources for certification.

Examples of GIA and HRD grading reports are typically provided with certified diamonds, helping buyers compare and verify quality.

Fluorescence

Fluorescence refers to a diamond's visible reaction to ultraviolet (UV) light . In environments with UV light—such as nightclubs or under a black light—some diamonds can emit a visible glow , most often blue .

Approximately 25–35% of diamonds exhibit some level of fluorescence , but only 2–3% of diamonds visibly affect their appearance. In very rare cases (less than 0.2%), intense fluorescence can cause the stone to appear cloudy or milky.

Interestingly, blue fluorescence can also enhance the appearance of yellow-toned diamonds (color I and above), making them appear whiter and brighter . In about 5% of cases, fluorescence can manifest itself in other colors, such as yellow, white, green, or even red—as occurs in the famous Hope Diamond.