17 April, 2018

WG Diamond Series - Cut

Read time 8-9 mins

The 4 Cs of the diamond world which dominates every purchase decision are; Cut, Clarity, Colour and Carat. Here we will take a look at one of the most important - Cut.

When it comes to buying diamonds, the cut of it will have the greatest impact on how the diamond reflects light and thus, affect its price.

First of all, when grading the cut of a diamond, it’s referring to the reflective qualities of the diamond and not its shape.

Here at William George & Co, you can find jewellery graded by GIA who is an industry-leading authority on Diamonds with nearly 90 years of experience. 

How Does a Diamond Achieve its Brilliance?

The cut of the diamond can have a significant impact on how it reflects light back to the observer. The light which reflects back through the diamond is called brilliance. Therefore, how well a diamond reflects light will be a sign of the quality of its cut.

If a diamond has a perfect clarity and colour grade, it can still be spoilt by an unequal cut as it can make the diamond appear to look dull.

How Are Diamonds Graded?

Here are examples of the grading certifications used to summarise the cut of a diamond.

  • Ideal – Reflects most of the light which enters the diamond. This category applies only to round diamonds (Highest grade for AGS).
  • Excellent - Reflects as much light as an ideal certified diamond (highest grade for GIA).
  • Very Good – Reflects near the same level as ideal/Excellent. These diamonds tend to be bigger in size.
  • Good - Reflects light that enters the diamond but not as much as very good. These diamonds are usually large and would be cut straight from the original rough crystal.
  • Fair & Poor – Appears dull or glassy. These diamonds have been cut to maximize the carat weight over most other considerations.

What is the Difference between Sparkle, Fire and Brilliance?

Words used to describe the diamond's ability to reflect light are; brilliance, sparkle (sometimes called scintillation) and fire. 

  • Brilliance – The total amount of light reflected through the diamond.
  • Sparkle – Also called scintillation. It describes the light which bounces between the different facets towards the centre of the diamond. The light which bounces off the facets is described as its scintillation.
  • Fire - The fire of a diamond will describe the level of dispersion of light into different colours. When the light returns through the table of the diamond, its fire is described as the different colours visible.

The Diamond Terms You Need to Know

When you break down a diamond, it contains different aspects of which are used to describe it.

  • Diameter - The width of the diamond which is measured through the girdle.
  • Girdle - The rim of a diamond that separates the crown and the pavilion. 
  • Culet - The tip of the bottom part of a diamond (pavilion).
  • Depth - From top to bottom, the height of a diamond.
  • Pavilion - Sometimes called the base of a diamond, it's the lower part of a diamond (below the girdle).
  • Table - This is the flat top of a diamond.
  • Crown - The upper part of a cut gemstone (located above the girdle).

How does Light Travel Through a Diamond?

Have you ever wondered how light travels through a diamond?

Two things you need to know are the pavilion and the table of a diamond. These two aspects come together to create the brilliance, sparkle and fire of a diamond. When light first enters a diamond through the table, it travels to the pavilion and then returns back-through the table.

A large table enables more light to travel into the diamond and tends to be brighter. A diamond with a smaller table will have a bigger crown which gives off more fire.

Trivia - The table’s reflection is the small octagon located in the centre of the diamond.

A poorly cut diamond will leak light. That is to say, when light enters, it will escape through the sides or the bottom as opposed to returning back to the observer.

Do Diamonds Leak Light?

When a diamond cut is too shallow, light hits the pavilion at a low angle. The light travels through the diamond and exits through the sides, instead of reflecting through the table and to your eyes.

While shallow cut diamonds may seem largely based on their table size, the escape of light at the bottom significantly reduces the diamond’s brilliance, sparkle and fire.

Final Words

Diamonds are truly worth a thousand words but there are still 3 more of the Cs to go through. If you liked the article then hit the share button. The next C to be explored is Colour. Hit the button below.

Diamond Guide - Cut