Diamond Education Anatomy of a diamond and the effects of light

The diamond structure

Features of a diamond

A diamond is made up of two key sections, the Crown and the Pavilion. Their structure and relationship to each other in the form of table and depth percentages have the biggest impact on the diamond’s sparkle.

The round brilliant cut has been used as an example, because with most other diamond shapes (“fancy cut” diamonds) the cut grading is more complicated (hence why their cut grading does not appear on certificates such as GIA).

Anatomy of a diamond

Diameter: Width of the diamond at the widest point of the girdle (in fancy cut diamonds, the smallest diameter is used).

Table: The largest facet at the top

Crown: The top part of the diamond between the girdle and the table

Girdle: The narrow band at the diamond’s widest point

Pavilion: The bottom part of the diamond between the girdle and the culet

Culet: The fact at the bottom tip (preferable when not visible to the naked eye)

Depth: The height of a diamond from the table to the culet

The Effects of Light on a Diamond

The science behind a diamond's brilliance depends on its great ability to bend, slow and direct light as it passes through. The cut of a diamond determines how well the diamond is able to re-direct the light back through the surface of the diamond. Light travelling at about 186,000 miles per second, when passing through a diamond is reduced to about 77,000 miles per second, close to the maximum for any other transparent substance (another reason why we are 77 Diamonds).

Effects of light on a diamond
Light effect A

A ray of light hits the diamond's surface. Some of the light enters, and part of the light reflects back. The immediate reflection is the light given off by the crown angles.

Light effect B

The remaining light enters the diamond and reflects toward the centre of the diamond. The light that bounces off the internal wall of the diamond is the refraction.

Light effect C

The ray of light then shoots to the surface through the top of the diamond. A colour spectrum is visible when light exits the diamond.


Cut grading Cut gradingLearn More Cut grading across shapes Cut grading across diamond shapesLearn More
Polishing process Polishing (cut) processLearn More Hearts and arrows Hearts and arrowsLearn More

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