Cut

A common mistake is to confuse cut with shape.

Shape refers to the general outward appearance of the diamond, (round, square, oval or pear). The cut of a diamond on the other hand refers to its angles and proportions and correspondingly its reflective qualities.

Whilst the Carat. Colour and Clarity are dictated by nature, the Cut is the most directly influenced by the human hand and is the most important of the four Cs.

A good cut gives a diamond its sparkle. The angles and proportions, the way the diamond is cut determines a diamond’s ability to handle light, and generate the corresponding brilliance.

In a diamond that is well-cut, light enters through the table and travels through the stone where it is reflected from one side to the other before the light is returned back to the viewers eye by way of a flash of fire that seems to come from the very heart of the stone. This bright white light is the brilliance we mentioned earlier, the spectral colours are the dispersion and it's this fiery flashing, that makes diamonds so tantalising and desirable.

1. Well cut

When a diamond is well cut, light is internally reflected from one facet to another and then dispersed back through the top of the stone.

2. Deep cut

When the cut of a diamond is too deep, the light that enters through the table once inside the stone, 'leaks' out from the sides or the bottom of the diamond rather than reflecting back to the eye. Less light reflected back to the eye means lower brilliance.

Note that the deep-cut diamond shown above will have a higher carat weight, but is clearly the less desirable stone!

3. Shallow cut

When the cut of a diamond is to shallow, the light that enters through the table once inside the stone, 'leaks' out from the sides or the bottom of the diamond rather than reflecting back to the eye. Less light reflected back to the eye means lower brilliance.

Note that the shallow-cut diamond shown above will have a bigger diameter or table spread, but is clearly the less desirable stone!

Proportions

Diamond graders and jewellers agree amongst themselves that the best cut diamonds are those that follow a strict set of mathematical formulae in the cutting process that has been calculated to optimise the reflective brilliance of the stone.

These formulae (calculated differently for the different stone shapes) are reflected in a diamond's proportions: how the depth is related to the diameter, and how the diameter of the table compares to the diameter of the diamond.

However, the variance in the proportions between an Ideal Cut and a Poor Cut can be difficult to discern by the casual observer.

Grading Standards

Since cut is so important to the “face up” beauty of the diamond, several grading standards have been developed to help consumers determine the quality of cut of a diamond. In general, these standards are:

Excellent » Very Good » Good » Fair » Poor

When you buy a diamond, it will be given a grade of cut, in one of the following categories
Selecting the grade of cut is really a matter of personal preference. To make the best selection, you need to understand the various grades. Please note that the descriptions below are only general guidelines.

Excellent

This range has very strict cutting parameters and combines the best in brilliance and fire. Due to the amount of time and skill it takes to make an excellent cut diamond, very few excellent cut diamonds are available – they are also the most expensive on the market. Excellent Cut diamonds are truly for the person who enjoys knowing that they have one of the finest diamonds that money can buy.

Very Good

This range is also of great beauty. There is slightly more liberty with cut specifications. The parameters of diamonds in this range will typically overlap with certain parameters of diamonds in the excellent grade. They are intended to provide maximum brilliance and fire. Generally, the price of these diamonds is slightly below that of Excellent Cuts thus representing Great Value.

Good

Diamonds in this grade reflect much of the light that enters them. Their proportions fall outside of the preferred cutting 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 Ideal cut quality diamond. Diamonds in this range can offer excellent cost-savings to customers who want to stay in a budget without over sacrificing quality or beauty.

Fair & Poor

A diamond graded as fair or poor reflects only a limited proportion of light that entering it. These diamonds have been cut to maximise the weight/size over beauty considerations. Typically, diamonds of these cuts may be found in retail mall jewellery stores as "value specials".

How To Buy	Cut	Colour	Clarity	Carat