Foundations · Chapter 01

What a diamond actually is

Carbon, crystal structure, light, and the difference between hardness and toughness.

Before color grades and carat weights, there is the material itself: a crystal with remarkable optical properties and a few vulnerabilities worth understanding.

A crystal made principally of carbon

A diamond is defined by both its chemical composition and its crystal structure. Its carbon atoms are arranged in a tightly bonded cubic lattice; graphite is also carbon, but its atoms are arranged differently, which is why the two materials behave so differently.

Worth remembering: A material is defined by structure as well as ingredients.

Hard does not mean unbreakable

Diamond is exceptionally resistant to scratching, which is what gemologists mean by hardness. It can still chip or cleave after a well-placed impact, especially at a pointed corner, thin girdle, or existing surface-reaching inclusion.

Worth remembering: Everyday durability depends on design, setting, and care—not hardness alone.

Why a polished diamond returns light

A diamond bends and disperses light strongly. Cutting arranges small polished surfaces, called facets, so light and contrast form brightness, colored fire, and scintillation—the flashes of light and dark seen as the stone, viewer, or light source moves.

The anatomy beneath the silhouette

The crown sits above the widest edge, or girdle; the pavilion descends below it; the table is the broad central facet; and the culet is the point or small facet at the bottom. These parts matter because their angles and relative sizes shape appearance and durability.

Diamond, simulant, and treatment are different ideas

A simulant such as cubic zirconia may resemble a diamond but is a different material. A treatment changes a diamond’s appearance after formation. Natural and laboratory-grown diamonds are both diamond material, but they have different origins that trained laboratories can distinguish.

Worth remembering: Ask about material, origin, and treatment as three separate questions.

Essential language

Crystal structure: The repeating internal arrangement of atoms in a crystalline material.
Facet: A flat, polished surface placed on a gemstone.
Girdle: The outer edge separating a diamond’s crown from its pavilion.
Simulant: A different material used to imitate the appearance of diamond.
Treatment: A process applied after formation to alter a gem’s color, clarity, or appearance.

Questions to take with you

Does the grading report identify the material as diamond?
Does the report state whether the diamond is natural or laboratory-grown?
Are any color or clarity treatments disclosed?
Does the shape have points or corners that need added protection?