Anatomy of a Diamond

Anatomy and structure of a cut diamond
ROSY DIAMOND KNOWLEDGE

Anatomy of a diamond

The table, crown, girdle, pavilion, and culet together form the visible architecture of a cut diamond.

Understanding these areas makes it easier to assess proportions, apparent size, and light performance.

FUNDAMENTALS

Why is a diamond’s anatomy important?

A cut diamond consists of precisely arranged surfaces and areas. Their sizes, angles, and relationships with one another influence both its appearance and the way it interacts with light.

Anatomy therefore helps you better understand details such as table, depth, diameter, or girdle in a grading report.

Important No single measurement determines quality on its own. The various proportions must always be considered together.
Table, crown, girdle, pavilion, and culet of a diamond
THE MAIN AREAS

From the table to the culet

A Round Brilliant can be broadly divided into five central areas.

  • Table – the large upper facet
  • Crown – the area above the rundist
  • Girdle – the outer edge at the greatest circumference
  • Pavilion – the lower section of the diamond
  • Culet – the lowest point or smallest lower facet
These terms frequently appear in gemological descriptions. They help describe proportions and cut structure precisely.
TABLE

The largest upper facet

The Table is the large, flat facet on the upper side of a cut diamond.

It forms a central entry and exit surface for light and is directly related to the crown, pavilion, and the other facets.

Do not assess table size in isolation A larger or smaller table is not automatically better. It must be suited to the diamond’s other proportions.
CROWN

The upper section of the diamond

The Crown lies between the table and girdle.

It consists of several facets whose angles and arrangement influence how light enters the diamond and which optical effects are created.

Crown Height

Describes the height of the crown in relation to the diamond as a whole.

Crown Angle

Describes the angle of certain crown facets and is part of the proportions system.

GIRDLE

The rundist connects the upper and lower sections.

The Girdle, or rundist, runs around the diamond’s greatest circumference and separates the crown from the pavilion.

It is also the area where a Diamond is often held in a setting.

The Girdle should be balanced. A very thin or very thick girdle can have other practical or proportional effects. Assessment therefore always takes place in the context of the specific Diamond.
PAVILION & CULET

The lower area of the Diamond

The Pavilion lies below the girdle. Its facets play a central role in the internal reflection of light.

At the very bottom is the Culet. In modern cuts, this area can be very small or appear optically almost like a point.

Culet is not simply a “hole.” It is the lower termination of the cut Diamond or, where applicable, a very small facet.
Girdle, Pavilion, Culet, and facets of a Diamond in detail
FACETS

The surfaces control the light

Facets are the precisely cut and polished surfaces of a Diamond.

Their size, angles, position, and symmetry determine how light is directed and reflected within the stone.

1

Geometry

Facets follow a planned cutting pattern.

2

Symmetry

The alignment of the facets influences the overall appearance.

3

Polish

Clean surfaces support a clear light performance.

LIGHT PATH

How anatomy and brilliance are connected

The path of light and internal reflection in a Diamond

Light mainly enters the Diamond through the upper area, is reflected by Pavilion facets, and can exit again through the top.

How efficiently this process works depends on the interaction of many proportions.

That is why Cut is more than a single number. Table, Crown, Pavilion, Depth, and angles work together as a system.
Measuring a Diamond's diameter and depth
DIAMETER & DEPTH

How large and how deep is the Diamond?

Diameter describes the diameter, or width from one side to the other, of a round Diamond.

Depth describes the total height from the table area to the bottom of the Diamond.

These specifications are usually documented in millimetres.

Carat weight and measurements are not the same thing. Two diamonds with the same carat weight can have different diameters and depths.
TABLE % & DEPTH %

What do percentage specifications mean?

In gemmological reports, certain proportions are often given as percentages.

Table %

Describes the Table size in relation to the diamond’s width.

Depth %

Describes the total depth in relation to the width or diameter.

No single percentage is a quality assessment. The values must be considered together with the Crown, Pavilion, symmetry, and the overall cut.
ANATOMY & VISIBLE SIZE

Why Proportions Affect Size

Part of a diamond’s weight lies below the girdle. If a stone has relatively deep proportions, more weight may be located in the Pavilion.

As a result, a diamond may appear smaller from above than a well-proportioned comparison stone despite having the same carat weight.

Visible size results from several factors. Carat, Diameter, Depth, Shape, and proportions should be read together.
IN THE GRADING REPORT

Which anatomical details may be documented?

Measurements

The length, width, and depth of the diamond.

Proportions

For example, Table, Depth, or other angle and ratio details.

Finish

Polish and symmetry may be assessed separately.

Depending on the shape and report, the scope and presentation of these details may vary.

ROSY Certificate Standard For a single lab-grown diamond of 0.50 ct or more, ROSY Lab Diamonds provides you with an independent IGI grading report as well as the ROSY product certificate.
BUYING ADVICE

Which anatomical values should I consider?

  • Consider carat weight and millimeter measurements together.
  • Do not assess Depth in isolation.
  • Understand the Table and remaining proportions as a system.
  • For Round Brilliant, check the available cut details.
  • For Fancy Shapes, also consider the length-to-width ratio and silhouette.
  • Take polish and symmetry into account.
  • Do not replace the diamond’s actual light performance with table values.
IN BRIEF

Diamond Anatomy at a Glance

  • Table is the large upper facet.
  • Crown lies between the Table and Girdle.
  • Girdle forms the largest outer circumference.
  • Pavilion lies below the girdle.
  • Culet forms the lower termination.
  • Facets work together to direct light.
  • Diameter describes the width; Depth describes the total depth.
  • Proportions must be considered as an interplay.
ROSY DIAMOND KNOWLEDGE

Understand anatomy. Read proportions correctly.

Anyone who understands a diamond’s structure can assess its cut, visible size, and grading report details much more effectively.

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