ダイヤモンドの 構造を知ろう

Let's learn about the structure of a diamond.

by Vien Chi Bao on Apr 03 2026
Table of Contents

    HuyK Jewelry · Diamond Guide

    Understanding the
    Diamond Structure

    A diamond is composed of multiple meticulously calculated parts. Understanding its structure is the first step toward unlocking the secret behind its brilliance.


    HuyK Jewelry  ·  March 2025  ·  DIAMOND GUIDE

    The beauty of a diamond is no accident. From the crown to the culet, every part is precisely designed to maximize the reflection, refraction, and dispersion of light. Learning the role of each part will change the way you view stones.

    Anatomy of a Diamond

    テーブル クラウン ガードル パビリオン ファセット キューレット
    01
    Table

    The largest, flat facet on top of the diamond. It serves as the primary "entrance" for light and is the most important part for defining the diamond's character. The size of the table is directly linked to its brilliance.

    02
    Crown

    The entire upper portion from the table to the girdle. Composed of multiple facets, it plays the role of capturing and dispersing light. The angle of the crown significantly influences the stone's fire (rainbow-colored flashes).

    03
    Girdle

    The band-like edge that forms the boundary between the crown and the pavilion. Known as the "waist" of the stone, it serves as the reference point for setting the diamond in jewelry. A uniform thickness is a hallmark of high quality.

    04
    Pavilion

    The inverted conical portion below the girdle. It acts as a mirror that performs total internal reflection to send light back through the table. The angle of the pavilion is the core element that dictates the quality of a diamond's sparkle.

    05
    Facet

    The collective term for the flat, polished surfaces on a diamond. A standard round brilliant cut has 58 facets. The angle, shape, and symmetry of each facet create the patterns of light reflection.

    06
    Culet

    The point at the very bottom of the pavilion, or a small flat facet. In modern cuts, it is finished to be extremely small or "none." If it is too large, light leaks out from the bottom, causing a loss of brilliance.

    Why Understanding the Structure Matters

    To properly understand the meaning of cut grades

    1
    Understand the mechanics of brilliance The process of light entry, total reflection, and light exit is determined by the proportions and angles of each part. Once you know the structure, you will naturally understand why "cut grade" is considered the most important evaluation metric.
    2
    Decipher grading reports Grading reports from organizations like the GIA contain technical data such as table percentage, pavilion depth, and girdle thickness. Knowing the names of these parts allows you to accurately grasp the meaning of these values.
    3
    Compare differences in cuts Facet counts and the proportions of specific parts vary depending on the cut shape, such as round brilliant, princess, or oval. A foundation in structure will help you make more informed choices when selecting a cut.

    When choosing a diamond, many people tend to focus on carat weight and price. However, even with the same carat weight and price, the brilliance can vary significantly based on the cut—or, in other words, the precision of its structure. Understanding a stone's anatomy is the key to cultivating a discerning eye for finding a truly beautiful gem.