Diamond Cut

Many people confuse diamond cut with diamond shape, however they are completely different things. Diamond shape is a term which refers to the outward appearance of a diamond stone. Examples of diamond shapes are: asscher, round, emerald, and heart. By comparison the term diamond cut refers to diamond’s reflective qualities, not the shape.

A diamond’s cut is arguably the most important of the four Cs, so it’s important to understand how the cut affects both the physical properties as well as the value of a diamond. A good cut gives a diamond its brilliance (the brightness that seems to come from the very center of a diamond). This brilliance is created from the angles and finish of a diamond, which affects the diamond’s ability to handle light.

When a diamond is well-cut, light enters at the table and travels through to the pavilion where it reflects from one side to the other before reflecting back out of the diamond through the table and to your eye. This light flashing effect is what makes diamonds sparkle.

If a diamond is poorly cut, the light which enters through the table reaches the facets and then ‘leaks’ out from the sides or bottom of the diamond rather than completely reflecting back to your eye. Less light reflected back to your eye obviously means less brilliance and sparkle.

Importance of Good Proportions

The vast majority of gemologists agree that the best cut diamonds are those that follow a set of formulae, which is calculated to maximize brilliance. The formulae can be seen in a diamond’s proportions. The two most important factors are how the depth compares to the diameter, and how the diameter of the table compares to the diameter of the diamond.

Since cut is so important, several grading methods have been developed to help consumers determine the cut of a particular diamond. The general grades which you see quoted are:

  • Ideal
  • Premium
  • Very Good
  • Good
  • Fair & Poor

Which Grades of Cut Should You Buy?

Choosing the grade of cut is really a matter of personal preference. In order to make an informed decision you need to understand the various grades. The following are general guidelines to help you decide which grade of cut you should buy.

Ideal Cut

The object of this cut is to maximize brilliance. This cut has typically smaller table sizes, which have the added benefit of creating a great deal of dispersion or ‘fire’ as well. Ideal quality diamonds are for people who enjoy the finest things that money can buy. Ideal cut is a category which only applies to round diamonds.


For round diamonds, a good many Premium Cut diamonds have cuts which are the equal of any Ideal Cut diamond. Despite this, they can often be purchased at slightly lower prices than Ideal Cuts. They are designed to provide maximum brilliance and fire. Like the Ideal Cut, these are also for people who enjoy the finer things in life.

Very Good

Very good cut diamonds reflect most of the light which enters them, creating a lot of brilliance. With very good cut diamonds, the cutters choose to stray slightly from the preferred diamond proportions in order to create a larger diamond. As a result these diamonds may fall slightly outside of some customers’ preferences in terms of, table size or girdle width, though, in many cases many of the parameters of diamonds in this range will overlap with certain parameters of diamonds in the Ideal or Premium ranges. Generally, these diamonds can be had for slightly lower prices than that of Premium cuts.


Good cut diamonds reflect much of the light that enters them. Their proportions fall outside of the preferred range because the cutter has chosen to create the largest possible diamond from the original rough crystal, rather than cutting extra weight off to create a smaller Premium quality diamond. Diamonds in this range offer can offer great value to customers who want to stay in a budget without sacrificing quality or beauty.

Fair and Poor

Diamonds graded as fair or poor cut will reflect only a small proportion of the light that enters them. They typically will have been cut to maximize the carat weight over other considerations.

Anatomy of a Diamond

If you are trying to figure out the difference between a diamond’s pavilion, table, or culet the following information will help explain the various parts of a diamond for you.

Diamond Sections


This is the upper portion of a cut gemstone, above the girdle.


This is the tiny facet on the pointed bottom of the pavilion, which is the portion of a cut gem below the girdle.


The depth is actually the height of a gemstone, from the culet to the table.


This is the width of the diamond as measured through the girdle.


The girdle is a narrow rim of a diamond that separates the crown from the pavilion. It is the largest diameter to any part of the stone.


The pavilion is the lower portion of the diamond, below the girdle. It can also be referred to as the base.