A diamond is a solid form of carbon arranged in a crystal structure, representing the hardest known natural material. Formed deep within the Earth’s mantle under immense pressure and heat, this transparent crystal is prized for its unique optical properties and durability. A single stone is described using a vocabulary that changes depending on its quality, source, and final geometric form. Understanding these names helps navigate the modern diamond market.
Terminology Based on the 4 Cs
The most standardized language used to classify and determine a diamond’s value is based on the system known as the 4 Cs: Carat, Color, Clarity, and Cut. Carat is the term used to name the weight of the stone, with one metric carat equaling 200 milligrams. For precision, the carat is subdivided into 100 points, meaning a 0.75-carat diamond may also be referred to as a “seventy-five pointer.”
Clarity describes the presence of internal characteristics (inclusions) and external characteristics (blemishes). Inclusions are features like trapped crystals or fractures that form inside the diamond during its creation. Blemishes are surface-level imperfections like scratches or nicks. Clarity names range from Flawless (FL), where no features are visible under 10x magnification, down through Very, Very Slightly Included (VVS) and Very Slightly Included (VS).
The scale continues to Slightly Included (SI) and finally Included (I), where features are noticeable under magnification and may be visible to the unaided eye. Color names for the typical colorless to near-colorless range are defined by a letter scale beginning with D, which represents a completely colorless stone. The grades continue through the alphabet to Z, describing diamonds with an increasing presence of light yellow or brown tint.
Diamonds that exhibit intense colors beyond the Z grade are named Fancy Colored diamonds; their value increases with the intensity and purity of the hue. The final C is Cut, which names the quality of the diamond’s proportions, symmetry, and polish, determining how well it interacts with light. Cut quality is graded with names like Excellent (or Ideal), Very Good, Good, Fair, and Poor, reflecting the diamond’s ability to return light as brilliance and fire.
Names Defined by Origin and Creation
Diamond names are also categorized based on their origin, differentiating stones mined from the earth from those created in a laboratory. Natural Diamonds are the traditional stones formed deep within the Earth over billions of years. Conversely, diamonds grown in a controlled environment are commonly referred to as Laboratory-Grown Diamonds (LGDs), Cultured Diamonds, or Synthetic Diamonds.
These lab-created stones are chemically and structurally identical to natural diamonds, but their names denote their method of production. The two primary methods produce stones named HPHT diamonds (High-Pressure/High-Temperature) and CVD diamonds (Chemical Vapor Deposition). HPHT diamonds are grown by mimicking the Earth’s natural conditions, while CVD diamonds are grown from a hydrocarbon gas mixture in a vacuum chamber.
Additional names are used for diamonds that have undergone post-growth processing to alter their appearance, known as Treated Diamonds or Enhanced Diamonds. Treatments to improve clarity include laser drilling and fracture filling, which make internal features less visible. Color enhancement treatments, such as subjecting a stone to HPHT after it has been mined, can convert a brownish tint to a near-colorless or even a Fancy color.
Finally, diamonds not suitable for jewelry are given industrial names based on their characteristics and purpose. Bort refers to low-quality, opaque, or fragmented diamond material used primarily as an abrasive. Carbonado, also called “black diamond,” is a polycrystalline, porous form of diamond used for drilling and cutting.
Common Names for Diamond Shapes
Distinct from the Cut Grade, which assesses light performance, the shape name describes the geometric outline and faceting pattern of a finished diamond. The most popular shape is the Round Brilliant, a circular stone cut with 57 or 58 facets designed to maximize brilliance. All other shapes are broadly named Fancy Shape Diamonds.
Square or rectangular shapes include the Princess Cut, a square shape with pointed corners and a brilliant-style facet pattern, and the Emerald Cut, which is rectangular with step-cut facets that create long, flashing reflections. The Cushion Cut is a hybrid, featuring a square or rectangular outline with rounded corners and a brilliant facet arrangement that resembles a pillow.
Elongated shapes are named for their distinctive outlines, such as the Oval, which offers a brilliant sparkle while often appearing larger than a round stone of the same weight. The Pear Cut is named for its teardrop shape, with one rounded end tapering to a single point. Another elongated shape is the Marquise, which is often described as boat-shaped, featuring points at both ends.
Identifying Diamond Simulants and Substitutes
It is important to differentiate diamonds, whether natural or lab-grown, from materials that merely imitate their appearance. These materials are named Diamond Simulants or Substitutes because they look similar to diamonds but possess a different chemical composition and crystal structure. Cubic Zirconia (CZ) is one of the most common man-made simulants, composed of zirconium dioxide.
Another popular simulant is Moissanite, which is silicon carbide, a material that exhibits greater fire, or light dispersion, than a natural diamond. While lab-grown diamonds are chemically carbon, simulants like CZ and Moissanite are entirely different substances that lack the same physical durability. Natural gemstones and inexpensive glass imitations are also used as substitutes, including:
- White Sapphire
- Topaz
- Rhinestones
- Paste