Diamond Table and Depth

This section covers all you need to know about how table and depth percentages affect the brilliance of diamond jewellery and engagement rings

The Importance Of Table Percentages And Values

A diamond’s table is the facet which can be seen when the stone is viewed face up. It is the largest facet on a diamond and plays a vital role in its brilliance and light performance. The main purpose of the table facet is to reflect rays entering the diamond and allow them to be reflected back from the pavilion.

Understanding Table Percentage

It’s a wide misconception that a larger table percentage would make a round cut diamond appear more brilliant. This is not the case, as there are other factors affecting the overall brilliance and fire of a diamond. Fire is best observed at the bezel facets of a diamond. With a limited amount of space at the crown area, a larger table would mean that the bezel and upper girdle facets would have less surface area and light dispersion would decrease. Having a small table would allow girdle facets to disperse light more effectively, while suffering from issues with brilliance. When choosing the diamond for an engagement ring,  wedding ring or any  diamond jewellery, it’s important to strike a balance between light transmission through the table and colour dispersion through the crown and upper girdle facets.

Understanding table percentage

How Is Table Percentage Calculated?

In a grading report, table percentage is calculated based on the size of the table, divided by the average girdle diameter of the diamond. A 60% table means that the table is 60% of the diamond’s outline width.

If the diamond is round, gemmologists can calculate this value by dividing the table diameter to the average girdle diameter, measured in millimetres. For a consumer, this can easily be calculated based on the average measurements found at a grading report’s top left-hand side.

For fancy shaped diamonds, table percentage is calculated by dividing the table width (measured at the widest part of the facet) to the width of the widest part of the stone, measured in millimetres. On a grading report, the width is the second of the three values under “Measurements” and is defined in millimetres.

How To Use Depth And Table Percentages Effectively

The depth and table percentages play a major role in the diamond ring’s beauty. They show how the stone has been cut in relation to its proportions and are usually one of the first few values to help you instantly remove diamonds with less ideal cuts. However, a diamond should not be rejected based solely on depth or table percentage, as the overall cut grade has already taken into consideration both factors. Depth and table percentages could be used to compare two diamonds with identical cut grade, for further refinements, especially regarding the size of the stone.

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